Methods for conveying additional information via beam permutations

ABSTRACT

Aspects are provided which allow a transmitting device to provide reference signals to a receiving device for beam management according to an arbitrarily determined sequence of transmission beams at any time, and to implicitly convey information regarding the determined sequence of transmission beams to the receiving device. The transmitting device provides a message to the receiving device indicating a beam sequence conveyance mode. The transmitting device subsequently determines a sequence of different transmission beams, and associates a reference signal with each one of the transmission beams for transmission to the receiving device according to the sequence. The receiving device obtains the plurality of reference signals from the transmitting device, where each of the reference signals is associated with a different transmission beam. The receiving device identifies a reception beam for each of the transmission beams, and determines a sequence of the transmission beams in response to the identification.

BACKGROUND Technical Field

The present disclosure generally relates to communication systems, andmore particularly, to communication between wireless devices such as auser equipment (UE) and a base station.

Introduction

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. 5G NR includes services associated with enhanced mobilebroadband (eMBB), massive machine type communications (mMTC), andultra-reliable low latency communications (URLLC). Some aspects of 5G NRmay be based on the 4G Long Term Evolution (LTE) standard. There existsa need for further improvements in 5G NR technology. These improvementsmay also be applicable to other multi-access technologies and thetelecommunication standards that employ these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may be a first wirelessdevice, such as a UE, a relay or sidelink node, a customer-premisesequipment (CPE), a repeater, or an integrated access and backhaul (IAB)node, which includes multiple antennas that may receive data over anygiven carrier frequency. The first wireless device may also be a basestation or a transmission reception point (TRP). The first wirelessdevice obtains a plurality of reference signals from a second wirelessdevice, where each of the reference signals is associated with adifferent transmission beam. The reference signals may be, for example,channel state information (CSI) reference signals (CSI-RS) (e.g., iffirst wireless device is a UE) or sounding reference signals (SRS)(e.g., if first wireless device is a base station). The first wirelessdevice identifies a reception beam for each of the transmission beamsand determines a sequence of the transmission beams in response to theidentification. The identified reception beams comprise differentreception beams or at least one common reception beam.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may be a first wirelessdevice, such as a base station, a TRP, a repeater, or an IAB node, whichincludes multiple antennas that may transmit data over any given carrierfrequency. The first wireless device provides a message to a secondwireless device indicating a beam sequence conveyance mode. The firstwireless device determines a sequence of different transmission beams,and associates a reference signal with each one of the transmissionbeams for transmission to the second wireless device according to thesequence. The reference signals may be, for example, channel stateinformation (CSI) reference signals (CSI-RS).

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIG. 2A is a diagram illustrating an example of a first frame, inaccordance with various aspects of the present disclosure.

FIG. 2B is a diagram illustrating an example of DL channels within asubframe, in accordance with various aspects of the present disclosure.

FIG. 2C is a diagram illustrating an example of a second frame, inaccordance with various aspects of the present disclosure.

FIG. 2D is a diagram illustrating an example of UL channels within asubframe, in accordance with various aspects of the present disclosure.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIG. 4 is a diagram illustrating an example of transmission beams from abase station and reception beams from a UE.

FIG. 5 is a diagram illustrating an example of distinguishable beampairs.

FIG. 6 is a diagram illustrating an example of CSI-RS symbols which thebase station transmits according to a pre-configured sequence oftransmission beams, where during each symbol the UE performs a singlesignal strength measurement over a different reception beam.

FIGS. 7A-7B are diagrams illustrating examples of CSI-RS symbols whichthe base station transmits according to different sequences oftransmission beams, where during each symbol the UE performs four signalstrength measurements over different reception beams.

FIG. 8 is a diagram illustrating an example of a chart showing arelationship between a number of searched reception beams and a datarate for a given number of CSI-RS symbols and different numbers of beamcandidates.

FIG. 9 is a diagram illustrating an example of CSI-RS symbols which thebase station transmits according to a determined sequence oftransmission beams, where during each symbol the UE performs two signalstrength measurements over different reception beams.

FIG. 10 is a diagram illustrating an example of CSI-RS symbols which thebase station transmits according to a determined sequence oftransmission beams in different transmission beam groups, where duringeach symbol the UE performs two signal strength measurements overdifferent reception beams.

FIG. 11 is a diagram illustrating another example of CSI-RS symbolswhich the base station transmits according to a determined sequence oftransmission beams in different transmission beam groups, where duringeach symbol the UE performs two signal strength measurements overdifferent reception beams.

FIG. 12 is a diagram illustrating a call flow between wireless devices.

FIG. 13 is a flowchart of a method of wireless communication.

FIG. 14 is a flowchart of another method of wireless communication.

FIG. 15 is a diagram illustrating an example of a hardwareimplementation for an example apparatus.

FIG. 16 is a diagram illustrating another example of a hardwareimplementation for another example apparatus.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

In millimeter wave (mmW) frequencies (e.g., frequency range 2 (FR2) orbeyond), a UE and base station may perform beamforming to improve gainand reliability of transmissions and to improve reception of transmittedsignals. To establish and retain an optimal beam pair (a transmissionbeam and a corresponding reception beam) for strong connectivity, the UEand base station may perform various beam management procedures. Suchprocedures may include, for instance, beam training (also referred to asa P1 procedure), transmission beam refinement (also referred to as a P2procedure), and reception beam refinement (also referred to as a P3procedure).

In beam training, a base station transmits a burst of synchronizationsignal blocks (SSBs) to a UE. The base station may transmit each SSBover a different transmission beam (referred to as transmission beamsweeping), and the UE may receive each SSB over multiple reception beams(referred to as reception beam sweeping). During transmission orreception beam sweeping, the UE determines K beam pairs (of transmissionand reception beams) which result in the highest signal strength (e.g.,reference signal received power (RSRP) or received signal strengthindicator (RSSI)) (i.e., the K best beam pairs). Upon determining the Kbest beam pairs, the UE reports these pair(s) to the base station inrandom access channel (RACH) occasions corresponding to the SSB(s)associated with the best beam pairs.

Following beam training, the base station and UE may performtransmission beam refinement or reception beam refinement. Intransmission beam refinement, a transmitting device sends multiplereference signal symbols (e.g., symbols carrying CSI-RS or SRS)respectively over different transmission beams, and a receiving devicereceives each reference signal symbol over a fixed reception beam.Contrarily, in reception beam refinement, the transmitting device sendsmultiple reference signal symbols over a fixed transmission beam, andthe receiving device receives each reference signal symbol respectivelyover different reception beams. The transmitting device and receivingdevice may be a base station and UE, respectively, or vice-versa. Duringtransmission beam or reception beam refinement, the receiving devicedetermines the beam pair resulting in the highest signal strength (e.g.,the best beam pair from the K best beam pairs), and the receiving devicereports this beam pair to the transmitting device. The base station andUE may then use this beam pair as a serving beam pair for downlink anduplink data transmission (e.g., in a physical downlink shared channel(PDSCH) or a physical uplink shared channel (PUSCH)), with the remainingbest beam pairs serving as fallback options for diversity in the case ofblockage, fading, etc., or other purposes (e.g., higher layertransmissions). For example, if the UE detects a beam failure in theserving beam pair, the UE and base station may switch to one of theremaining beam pairs during beam failure recovery. Moreover, during beamtracking or beam management, the UE may perform a low overhead scan ofthe K best beam pairs periodically during radio link monitoring (RLM)(typically by measuring signal strength of CSI-RS symbols) in order tomaintain updated beam pairs for subsequent beam refinement.

Thus, during beam management, a transmitting device may providereference signals over various transmission beams for a receiving deviceto perform beam signal strength measurements. However, a transmittingdevice generally does not convey information to the receiving deviceregarding the sequence of the various transmission beams. Rather, thetransmitting device generally selects the transmission beams accordingto a fixed sequence that is pre-configured prior to beam management, andthe transmitting device does not arbitrarily change this beam sequence.Moreover, the transmitting device typically provides reference signalsduring beam management in response to conditions such as blockage orinterference or other factors triggering beam failure recovery, ratherthan unconditionally at any time.

Hence, aspects of the present disclosure allow a transmitting device toprovide reference signals to a receiving device for beam managementaccording to an arbitrarily determined sequence of transmission beams atany time. Aspects of the present disclosure also allow the transmittingdevice to implicitly convey information regarding the determinedsequence of transmission beams to the receiving device. The transmittingdevice may implicitly convey information regarding transmission beamsequences during beam management if the receiving device is capable ofperforming multiple, simultaneous radio frequency (RF) signal strengthmeasurements of reference signals during each symbol. Such implicitconveyance of transmission beam sequences may result in reduced overheadcompared to explicit messages indicating the beam sequence, therebysaving resources. Moreover, the transmitting device may change atransmission beam sequence (e.g., to a sequence other than apre-configured sequence for beam management) at any time, regardless ofblockage or interference or similar beam failure conditions, since thereceiving device may be able to determine the sequence during themeasurement process.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, user equipment(s) (UE) 104, an Evolved Packet Core (EPC)160, and another core network 190 (e.g., a 5G Core (5GC)). The basestations 102 may include macrocells (high power cellular base station)and/or small cells (low power cellular base station). The macrocellsinclude base stations. The small cells include femtocells, picocells,and microcells.

The base stations 102 configured for 4G Long Term Evolution (LTE)(collectively referred to as Evolved Universal Mobile TelecommunicationsSystem (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interfacewith the EPC 160 through first backhaul links 132 (e.g., S1 interface).The base stations 102 configured for 5G New Radio (NR) (collectivelyreferred to as Next Generation RAN (NG-RAN)) may interface with corenetwork 190 through second backhaul links 184. In addition to otherfunctions, the base stations 102 may perform one or more of thefollowing functions: transfer of user data, radio channel ciphering anddeciphering, integrity protection, header compression, mobility controlfunctions (e.g., handover, dual connectivity), inter-cell interferencecoordination, connection setup and release, load balancing, distributionfor non-access stratum (NAS) messages, NAS node selection,synchronization, radio access network (RAN) sharing, MultimediaBroadcast Multicast Service (MBMS), subscriber and equipment trace, RANinformation management (RIM), paging, positioning, and delivery ofwarning messages. The base stations 102 may communicate directly orindirectly (e.g., through the EPC 160 or core network 190) with eachother over third backhaul links 134 (e.g., X2 interface). The firstbackhaul links 132, the second backhaul links 184, and the thirdbackhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y megahertz (MHz) (e.g., 5, 10, 15, 20, 100, 400,etc. MHz) bandwidth per carrier allocated in a carrier aggregation of upto a total of Yx MHz (x component carriers) used for transmission ineach direction. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 158. The D2D communication link 158 may use theDL/UL WWAN spectrum. The D2D communication link 158 may use one or moresidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communication may be through a variety of wireless D2Dcommunications systems, such as for example, WiMedia, Bluetooth, ZigBee,Wi-Fi based on the Institute of Electrical and Electronics Engineers(IEEE) 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint

(AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154, e.g., in a 5 gigahertz (GHz) unlicensedfrequency spectrum or the like. When communicating in an unlicensedfrequency spectrum, the STAs 152/AP 150 may perform a clear channelassessment (CCA) prior to communicating in order to determine whetherthe channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same unlicensed frequencyspectrum (e.g., 5 GHz, or the like) as used by the Wi-Fi AP 150. Thesmall cell 102′, employing NR in an unlicensed frequency spectrum, mayboost coverage to and/or increase capacity of the access network.

The electromagnetic spectrum is often subdivided, based onfrequency/wavelength, into various classes, bands, channels, etc. In 5GNR, two initial operating bands have been identified as frequency rangedesignations FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). Thefrequencies between FR1 and FR2 are often referred to as mid-bandfrequencies. Although a portion of FR1 is greater than 6 GHz, FR1 isoften referred to (interchangeably) as a “sub-6 GHz” band in variousdocuments and articles. A similar nomenclature issue sometimes occurswith regard to FR2, which is often referred to (interchangeably) as a“millimeter wave” band in documents and articles, despite beingdifferent from the extremely high frequency (EHF) band (30 GHz-300 GHz)which is identified by the International Telecommunications Union (ITU)as a “millimeter wave” band.

With the above aspects in mind, unless specifically stated otherwise, itshould be understood that the term “sub-6 GHz” or the like if usedherein may broadly represent frequencies that may be less than 6 GHz,may be within FR1, or may include mid-band frequencies. Further, unlessspecifically stated otherwise, it should be understood that the term“millimeter wave” or the like if used herein may broadly representfrequencies that may include mid-band frequencies, may be within FR2, ormay be within the EHF band.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include and/or be referred to as an eNB, gNodeB(gNB), or another type of base station. Some base stations, such as gNB180 may operate in a traditional sub 6 GHz spectrum, in millimeter wavefrequencies, and/or near millimeter wave frequencies in communicationwith the UE 104. When the gNB 180 operates in millimeter wave or nearmillimeter wave frequencies, the gNB 180 may be referred to as amillimeter wave base station. The millimeter wave base station 180 mayutilize beamforming 182 with the UE 104 to compensate for the path lossand short range. The base station 180 and the UE 104 may each include aplurality of antennas, such as antenna elements, antenna panels, and/orantenna arrays to facilitate the beamforming.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMEs 164, a Serving Gateway 166, an MBMS Gateway 168, a BroadcastMulticast Service Center (BM-SC) 170, and a Packet Data Network (PDN)Gateway 172. The MME 162 may be in communication with a Home SubscriberServer (HSS) 174. The MME 162 is the control node that processes thesignaling between the UEs 104 and the EPC 160. Generally, the MME 162provides bearer and connection management. All user Internet protocol(IP) packets are transferred through the Serving Gateway 166, whichitself is connected to the PDN Gateway 172. The PDN Gateway 172 providesUE IP address allocation as well as other functions. The PDN Gateway 172and the BM-SC 170 are connected to the IP Services 176. The IP Services176 may include the Internet, an intranet, an IP Multimedia Subsystem(IMS), a PS Streaming Service, and/or other IP services. The BM-SC 170may provide functions for MBMS user service provisioning and delivery.The BM-SC 170 may serve as an entry point for content provider MBMStransmission, may be used to authorize and initiate MBMS Bearer Serviceswithin a public land mobile network (PLMN), and may be used to scheduleMBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMStraffic to the base stations 102 belonging to a Multicast BroadcastSingle Frequency Network (MBSFN) area broadcasting a particular service,and may be responsible for session management (start/stop) and forcollecting eMBMS related charging information.

The core network 190 may include a Access and Mobility ManagementFunction (AMF) 192, other AMFs 193, a Session Management Function (SMF)194, and a User Plane Function (UPF) 195. The AMF 192 may be incommunication with a Unified Data Management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides Quality of Service(QoS) flow and session management. All user IP packets are transferredthrough the UPF 195. The UPF 195 provides UE IP address allocation aswell as other functions. The UPF 195 is connected to the IP Services197. The IP Services 197 may include the Internet, an intranet, an IMS,a Packet Switch (PS) Streaming Service, and/or other IP services.

The base station may include and/or be referred to as a gNB, Node B,eNB, an access point, a base transceiver station, a radio base station,a radio transceiver, a transceiver function, a basic service set (BSS),an extended service set (ESS), a transmit reception point (TRP), or someother suitable terminology. The base station 102 provides an accesspoint to the EPC 160 or core network 190 for a UE 104. Examples of UEs104 include a cellular phone, a smart phone, a session initiationprotocol (SIP) phone, a laptop, a personal digital assistant (PDA), asatellite radio, a global positioning system, a multimedia device, avideo device, a digital audio player (e.g., MP3 player), a camera, agame console, a tablet, a smart device, a wearable device, a vehicle, anelectric meter, a gas pump, a large or small kitchen appliance, ahealthcare device, an implant, a sensor/actuator, a display, or anyother similar functioning device. Some of the UEs 104 may be referred toas IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heartmonitor, etc.). The UE 104 may also be referred to as a station, amobile station, a subscriber station, a mobile unit, a subscriber unit,a wireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology.

Although the present disclosure may focus on 5G NR, the concepts andvarious aspects described herein may be applicable to other similarareas, such as LTE, LTE-Advanced (LTE-A), Code Division Multiple Access(CDMA), Global System for Mobile communications (GSM), or otherwireless/radio access technologies.

Referring again to FIG. 1, in certain aspects, the UE 104 or basestation 180 may include a beam sequence determination component 198 thatis configured to obtain a plurality of reference signals from a wirelessdevice (e.g., a UE or base station), where each of the reference signalsis associated with a different transmission beam. The beam sequencedetermination component is also configured to identify a reception beamfor each of the transmission beams, where the identified reception beamscomprise different reception beams or at least one common receptionbeam, and determine a sequence of the transmission beams in response tothe identification.

Still referring to FIG. 1, in certain aspects, the base station 180 mayinclude a beam sequence conveyance component 199 that is configured toprovide a message to a wireless device (e.g., a UE) indicating a beamsequence conveyance mode. The beam sequence conveyance component is alsoconfigured to determine a sequence of different transmission beams, andassociate a reference signal with each one of the transmission beams fortransmission to the wireless device according to the sequence.

FIG. 2A is a diagram 200 illustrating an example of a first subframewithin a 5G NR frame structure. FIG. 2B is a diagram 230 illustrating anexample of DL channels within a 5G NR subframe. FIG. 2C is a diagram 250illustrating an example of a second subframe within a 5G NR framestructure. FIG. 2D is a diagram 280 illustrating an example of ULchannels within a 5G NR subframe. The 5G NR frame structure may befrequency division duplexed (FDD) in which for a particular set ofsubcarriers (carrier system bandwidth), subframes within the set ofsubcarriers are dedicated for either DL or UL, or may be time divisionduplexed (TDD) in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G NRframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and F isflexible for use between DL/UL, and subframe 3 being configured withslot format 34 (with mostly UL). While subframes 3, 4 are shown withslot formats 34, 28, respectively, any particular subframe may beconfigured with any of the various available slot formats 0-61. Slotformats 0, 1 are all DL, UL, respectively. Other slot formats 2-61include a mix of DL, UL, and flexible symbols. UEs are configured withthe slot format (dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription infra applies also to a 5G NR frame structure that is TDD.

Other wireless communication technologies may have a different framestructure and/or different channels. A frame, e.g., of 10 milliseconds(ms), may be divided into 10 equally sized subframes (1 ms). Eachsubframe may include one or more time slots. Subframes may also includemini-slots, which may include 7, 4, or 2 symbols. Each slot may include7 or 14 symbols, depending on the slot configuration. For slotconfiguration 0, each slot may include 14 symbols, and for slotconfiguration 1, each slot may include 7 symbols. The symbols on DL maybe cyclic prefix (CP) orthogonal frequency-division multiplexing (OFDM)(CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for highthroughput scenarios) or discrete Fourier transform (DFT) spread OFDM(DFT-s-OFDM) symbols (also referred to as single carrierfrequency-division multiple access (SC-FDMA) symbols) (for power limitedscenarios; limited to a single stream transmission). The number of slotswithin a subframe is based on the slot configuration and the numerology.For slot configuration 0, different numerologies μ 0 to 4 allow for 1,2, 4, 8, and 16 slots, respectively, per subframe. For slotconfiguration 1, different numerologies 0 to 2 allow for 2, 4, and 8slots, respectively, per subframe. Accordingly, for slot configuration 0and numerology μ, there are 14 symbols/slot and 2^(μ) slots/subframe.The subcarrier spacing and symbol length/duration are a function of thenumerology. The subcarrier spacing may be equal to 2^(μ)*15 kilohertz(kHz), where μ is the numerology 0 to 4. As such, the numerology μ=0 hasa subcarrier spacing of 15 kHz and the numerology μ=4 has a subcarrierspacing of 240 kHz. The symbol length/duration is inversely related tothe subcarrier spacing. FIGS. 2A-2D provide an example of slotconfiguration 0 with 14 symbols per slot and numerology μ=2 with 4 slotsper subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60kHz, and the symbol duration is approximately 16.67 μs. Within a set offrames, there may be one or more different bandwidth parts (BWPs) (seeFIG. 2B) that are frequency division multiplexed. Each BWP may have aparticular numerology.

A resource grid may be used to represent the frame structure. Each timeslot includes a resource block (RB) (also referred to as physical RBs(PRBs)) that extends 12 consecutive subcarriers. The resource grid isdivided into multiple resource elements (REs). The number of bitscarried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot)signals (RS) for the UE. The RS may include demodulation RS (DM-RS)(indicated as R_(x) for one particular configuration, where 100x is theport number, but other DM-RS configurations are possible) and channelstate information reference signals (CSI-RS) for channel estimation atthe UE. The RS may also include beam measurement RS (BRS), beamrefinement RS (BRRS), and phase tracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs), each CCE includingnine RE groups (REGs), each REG including four consecutive REs in anOFDM symbol. A PDCCH within one BWP may be referred to as a controlresource set (CORESET). Additional BWPs may be located at greater and/orlower frequencies across the channel bandwidth. A primarysynchronization signal (PSS) may be within symbol 2 of particularsubframes of a frame. The PSS is used by a UE 104 to determinesubframe/symbol timing and a physical layer identity. A secondarysynchronization signal (SSS) may be within symbol 4 of particularsubframes of a frame. The SSS is used by a UE to determine a physicallayer cell identity group number and radio frame timing. Based on thephysical layer identity and the physical layer cell identity groupnumber, the UE can determine a physical cell identifier (PCI). Based onthe PCI, the UE can determine the locations of the aforementioned DM-RS.The physical broadcast channel (PBCH), which carries a masterinformation block (MIB), may be logically grouped with the PSS and SSSto form a synchronization signal (SS)/PBCH block (also referred to as SSblock (SSB)). The MIB provides a number of RBs in the system bandwidthand a system frame number (SFN). The physical downlink shared channel(PDSCH) carries user data, broadcast system information not transmittedthrough the PBCH such as system information blocks (SIBs), and pagingmessages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. The UE may transmit sounding referencesignals (SRS). The SRS may be transmitted in the last symbol of asubframe. The SRS may have a comb structure, and a UE may transmit SRSon one of the combs. The SRS may be used by a base station for channelquality estimation to enable frequency-dependent scheduling on the UL.

FIG. 2D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and hybrid automatic repeatrequest (HARD) acknowledgement (ACK)/non-acknowledgement (NACK)feedback. The PUSCH carries data, and may additionally be used to carrya buffer status report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter radio access technology (RAT) mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC servicedata units (SDUs), re-segmentation of RLC data PDUs, and reordering ofRLC data PDUs; and MAC layer functionality associated with mappingbetween logical channels and transport channels, multiplexing of MACSDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs,scheduling information reporting, error correction through HARQ,priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 316, 368, the RX processor 356, 370,and the controller/processor 359, 375 may be configured to performaspects in connection with beam sequence determination component 198 ofFIG. 1.

At least one of the TX processor 316, the RX processor 370, and thecontroller/processor 375 may be configured to perform aspects inconnection with beam sequence conveyance component 199 of FIG. 1.

In mmW frequencies (e.g., FR2 or beyond), a UE and base station mayperform beamforming to improve gain and reliability of transmissions andto improve reception of transmitted signals. To establish and retain anoptimal beam pair (a transmission beam and a corresponding receptionbeam) for strong connectivity, the UE and base station may performvarious beam management procedures. Such procedures may include, forinstance, beam training (also referred to as a P1 procedure),transmission beam refinement (also referred to as a P2 procedure), andreception beam refinement (also referred to as a P3 procedure).

In beam training, a base station transmits a burst of SSBs to a UE. Thebase station may transmit each SSB over a different transmission beam(referred to as transmission beam sweeping), and the UE may receive eachSSB over multiple reception beams (referred to as reception beamsweeping). During transmission or reception beam sweeping, the UEdetermines K pairs of transmission and reception beams which result inthe highest signal strength (e.g., RSRP or RSSI) (i.e., the K best beampairs). Upon determining the K best beam pairs, the UE reports thesepair(s) to the base station in RACH occasions corresponding to theSSB(s) associated with the best beam pairs.

FIG. 4 illustrates an example 400 of transmission beams 402 andreception beams 404 respectively swept by a base station 406 and UE 408during beam training. In this example, the base station may transmitSSBs over multiple transmission beams each having a potentiallydifferent direction, including transmission beams A, B, C, and D.Similarly, the UE may receive each SSB over multiple reception beamseach having a potentially different direction, including reception beamsX, Y, Z, and W. The UE may measure signal strengths for each pair oftransmission beams and reception beams. For instance, the UE may measuresignal-to-noise ratios (SNRs) associated with beam pairs AX(transmission beam A and reception beam X), AY, AZ, and AW, followed byBX, BY, BZ, and BW, and so forth. Afterwards, the UE may determine the Kbeam pairs having the highest signal strength out of the variousmeasured signal strengths. For instance, the UE may determine that thebeam pairs having the four highest signal strengths (i.e., K=4) includeAX, BY, CZ, and DW. The UE may subsequently report these best beam pairsto the base station in corresponding RACH occasions.

Following beam training, the base station and UE may performtransmission beam refinement or reception beam refinement. Intransmission beam refinement, a transmitting device sends multiplereference signal symbols (e.g., symbols carrying CSI-RS or SRS)respectively over different transmission beams, and a receiving devicereceives each reference signal symbol over a fixed reception beam.Contrarily, in reception beam refinement, the transmitting device sendsmultiple reference signal symbols over a fixed transmission beam, andthe receiving device receives each reference signal symbol respectivelyover different reception beams. The transmitting device and receivingdevice may be a base station and UE, respectively, or vice-versa. Duringtransmission beam or reception beam refinement, the receiving devicedetermines the beam pair resulting in the highest signal strength (e.g.,the best beam pair from the K best beam pairs), and the receiving devicereports this beam pair to the transmitting device. The base station andUE may then use this beam pair as a serving beam pair for downlink anduplink data transmission (e.g., in a PDSCH or a PUSCH), with theremaining best beam pairs serving as fallback options for diversity incase of blockage, fading, etc., or other purposes. For example, if theUE detects a beam failure in the serving beam pair, the UE and basestation may switch to one of the remaining beam pairs during beamfailure recovery. Moreover, during beam tracking or beam management, theUE may perform a low overhead scan of the K best beam pairs periodicallyduring RLM (typically by measuring signal strength of CSI-RS symbols) inorder to maintain updated beam pairs for subsequent beam refinement.

Thus, during beam management, a transmitting device may providereference signals over various transmission beams for a receiving deviceto perform beam signal strength measurements. However, a transmittingdevice generally does not convey information to the receiving deviceregarding the sequence of the various transmission beams. Rather, thetransmitting device generally selects the transmission beams accordingto a fixed sequence that is pre-configured prior to beam management, andthe transmitting device does not arbitrarily change this beam sequenceunless indicated so by the receiving device in the form of a beam switchrequest or command. Moreover, the transmitting device typically providesreference signals during beam management in response to conditions suchas blockage or interference or other factors triggering beam failurerecovery, rather than unconditionally at any time.

Hence, aspects of the present disclosure allow a transmitting device toprovide reference signals to a receiving device for beam managementaccording to an arbitrarily determined sequence of transmission beams atany time. Aspects of the present disclosure also allow the transmittingdevice to implicitly convey information regarding the determinedsequence of transmission beams to the receiving device. The transmittingdevice may implicitly convey information regarding transmission beamsequences during beam management if the receiving device is capable ofperforming multiple, simultaneous RF signal strength measurements ofreference signals during each symbol. Such implicit informationconveyance of transmission beam sequences may result in increased datarates achievable without a need for explicit messages indicating thebeam sequence by taking advantage of the device capability to performmultiple, simultaneous RF measurements. Moreover, the transmittingdevice may change a transmission beam sequence (e.g., to a sequenceother than a pre-configured sequence for beam management) at any time,regardless of blockage or interference or similar beam failureconditions, since the receiving device may be able to determine thesequence during the measurement process.

In one example, a UE may provide a capability report to a base stationindicating that the UE is capable of performing multiple simultaneoussignal strength measurements during a symbol length. In response to thecapability report, the base station may provide a message to the UEindicating a beam sequence information conveyance mode. Based on themessage, the UE may determine that subsequent symbols will conveyinformation for signal strength measurements for beam management (e.g.,CSI-RS), as well as information regarding a transmission beam sequencearbitrarily determined by the base station. Moreover in response to themessage, the UE may provide to the base station a set of distinguishablebeam pairs, e.g., the K best beam pairs obtained during beam trainingwhich meet certain signal strength conditions as described below withrespect to FIG. 5.

Next, the base station may determine a sequence of transmission beamsfrom the distinguishable beam pairs. Subsequently, during beammanagement, the base station may provide CSI-RS symbols to the UE overdifferent transmission beams according to the determined beam sequence.The UE may perform multiple, simultaneous RF measurements of RSRP orRSSI (or an equivalent signal strength metric) during each CSI-RS symbolfor different reception beams, in response to which measurements the UEmay identify the reception beams corresponding to distinguishable beampairs. The UE may then determine the sequence of transmission beams inresponse to the identified reception beams. In this way, beam managementaccording to arbitrarily determined transmission beam sequences forCSI-RS may be achieved.

Such a process may be similarly applied for SRS if the base station isable to perform multiple, simultaneous RF measurements during each SRSsymbol, in which case the base station may similarly determine asequence of transmission beams implicitly conveyed by the UE. Forexample, during beam management, the UE may provide SRS symbols to thebase station over different transmission beams according to a beamsequence arbitrarily determined by the UE. The base station may thenperform multiple, simultaneous RF measurements of RSRP or RSSI (or anequivalent signal strength metric) during each SRS symbol for differentreception beams, in response to which measurements the base station mayidentify the reception beams corresponding to distinguishable beampairs. The base station may then determine the sequence of transmissionbeams in response to the identified reception beams. In this way, beammanagement according to arbitrarily determined transmission beamsequences for SRS may similarly be achieved.

A receiving device (e.g., a UE or base station) may include RF circuitryor other capability that allows the receiving device to performmultiple, simultaneous RF measurements during a symbol length. In oneexample, the receiving device may include multiple RF chains (e.g.,multiple mixers, analog-to-digital converters (ADCs), digital-to-analogconverters (DACs), or other components). Multiple RF chains may allowfor higher data rates (e.g. higher numbers of layers or data streams),improved diversity and robustness, hybrid beamforming, and otherimprovements in comparison to a single RF chain. With multiple RFchains, the receiving device may independently perform beam scanningacross the different RF chains. However, such capability may result inhigher cost, larger usage of on-chip area, and higher power consumptionthan a single RF chain system. In another example, the network may allowthe receiving device to process sub-symbol level information (or thereceiving device may be capable of such processing). For example, a basestation may provide PSS, SSS, and DM-RS in PBCH at 240 kHz or largersubcarrier spacing (SCS), which the UE may measure multiple times over asingle SSB occasion in contrast to data or control information providedat 120 kHz or smaller SCS. Hence, the UE may measure PSS, SSS, and DM-RSin SSBs sub-symbol (i.e., multiple times in a symbol at 120 kHz orsmaller SCS). In a further example, the receiving device may include RFcircuitry that does not incorporate mixers, ADCs, DACs, or othercomponents typical in an RF chain (and thus does not include circuitryfor down converting received signals to intermediate frequencies (IF) orbaseband frequencies and further processing), but may still allow for RFmeasurements. Such RF circuitry may typically be found in wake-upreceivers (WURs), which are common in FR2 as well as FR1 to providepower savings. For instance, WURs do not demodulate signals buttypically search for power indicating a signal strength spike at aparticular frequency, and if power is detected (e.g., a measured RSRP isabove a threshold), the WUR wakes up a full receiver of the device todecode the paging channel the next time the page is sent. The receivingdevice may include such WUR RF circuitry. In an additional example, thereceiving device may include autonomous beam search circuitry, such asused in radar systems. This circuitry may be implemented in the form ofone or more self-steering arrays that have a state machine which rapidlycycles through several beam directions and detects the received signalamplitude in each direction.

Thus, a receiving device may include multiple RF chains, includesub-symbol level processing capability, include WUR RF circuitry,include autonomous beam search circuitry, or include other powerdetector(s) that allow the receiving device to measure signal strengthsover different reception beams multiple times during a symbol length.Nevertheless, some challenges remain in that power detectors tend tohave limited dynamic range, wide bandwidth requiring good filters, ormore limited dynamic range in on-chip detectors than test equipmentpower detectors. However, in cases where the signal strength of receivedsignals (e.g., RSSI) is sufficiently high, or in cases where appropriatefiltering is present before the signal reaches the detector, thereceiving device may incorporate any of the aforementioned circuitry orsimilar capability (e.g., power, voltage, or current detectors) toperform multiple RF measurements during a symbol length.

During beam training as described above, a receiving device may measureSNRs for multiple pairs of transmission (Tx) beams and reception (Rx)beams and identify the K best beam pairs. Following measurement of theSNRs, the receiving device may determine whether any of these best beampairs are distinguishable beam pairs. For example, the receiving devicemay identify a set of L distinguishable beam pairs, where L≤K. A set ofdistinguishable beam pairs may be defined to include those best beampairs (TxBeam(i), RxBeam(i)) associated with an SNR(i) for i=1 to L,where the difference between SNR(i) and a maximum SNR out of the SNRsassociated with beam pairs (TxBeam(i), RxBeam(j)) for j≠i is larger thanor equal to a signal strength threshold SNR_(threshold). For example, ifbeam pairs AX, AY, AZ, and AW are respectively associated with SNRs 25dB, 12 dB, 4 dB, and −2 dB respectively, where SNR_(threshold)=7 dB,then best beam pair AX is a distinguishable beam pair since thedifference between its SNR (i.e., 25 dB) and the maximum SNR out of theSNRs associated with the other beam pairs AY, AZ, and AW (i.e., 12 dB,leading to a difference of 25−12=13 dB) exceeds SNR_(threshold) (i.e.,13 dB>7 dB). Thus, distinguishable beam pairs may be considered to bebest beam pairs having SNRs which are distinguishably higher (relativeto SNR_(threshold)) than those of other beam pairs sharing a sametransmission beam. SNR_(threshold) may be a pre-configured signalstrength threshold which the receiving device may determine.Alternatively, the transmitting device may configure and provideSNR_(threshold) to the receiving device. After the receiving deviceidentifies the distinguishable beam pairs during the beam trainingprocess, the receiving device may report the set of distinguishable beampairs to the transmitting device.

FIG. 5 illustrates an example 500 of distinguishable beam pairs 502which a receiving device may determine during beam training. Similar tothe example described above in FIG. 4, in this illustrated example thetransmitting device has transmitted SSBs across four transmission beamsA, B, C, D, and the receiving device has received each SSB over fourreception beams X, Y, Z, W. Accordingly, the receiving device hasmeasured SNRs 504 of sixteen beam pairs, including AX, AY, AZ, AW, BX,BY, BZ, BW, CX, CY, CZ, CW, DX, DY, DZ, and DW. Examples of an SNRmeasurement for each beam pair is illustrated in FIG. 5, although inother examples different SNR values may be measured. Similarly, in otherexamples, the transmitting device may sweep across a different number oftransmission beams, the receiving device may sweep across a differentnumber of reception beams, and the receiving device may measure SNRvalues for a different number of beam pairs accordingly. Here, thereceiving device has determined that AX, BY, CZ, and DW are the K bestbeam pairs respectively for each transmission beam since these beampairs have the highest SNRs in each column. Moreover, assumingSNR_(threshold)=7 dB in this example, the receiving device hasdetermined that all of these best beam pairs are distinguishable beampairs, since the difference between the SNR of AX and the maximum SNR of(AY, AZ, AW), the difference between the SNR of BY and the maximum SNRof (BX, BZ, BW), the difference between the SNR of CZ and the maximumSNR of (CX, CY, CW), and the difference between the SNR of DW and themaximum SNR of (DX, DY, DZ), are all equal to or larger thanSNR_(threshold). Thus, following beam training, the receiving device mayreport to the transmitting device the best beam pairs AX, BY, CZ, and DWas a set of distinguishable beam pairs.

FIG. 6 illustrates an example 600 of CSI-RS symbols 602 that a basestation may transmit to a UE during beam management (e.g., beamrefinement), assuming the UE has reported AX, BY, CZ, and DW as the bestL distinguishable beam pairs as described above. While this examplespecifically refers to CSI-RS from a base station to a UE, similarprinciples may apply for SRS from a UE to a base station, or for CSI-RSor SRS between other wireless devices. In this example, the base stationgenerally provides M CSI-RS symbols to the UE according to a fixedsequence of transmission beams. For example, the base station maytransmit M=4 CSI-RS symbols to the UE over a pre-configured sequence oftransmission beams A, B, C, and D, respectively, in that order.Moreover, a UE capable of only performing one measurement per symbol mayattempt to receive the modulated CSI-RS symbols over a sequence ofreception beams X, Y, Z, and W, respectively, in that order, estimatethe RSRPs of the CSI-RS, and report the measurement results to the basestation. For example, as illustrated in FIG. 6, the UE may attempt toreceive over reception beam X the first CSI-RS symbol carried overtransmission beam A and measure one SNR for beam pair AX accordingly,the UE may next attempt to receive over reception beam Y the secondCSI-RS symbol carried over transmission beam B and measure one SNR forbeam pair BY accordingly, the UE may then attempt to receive overreception beam Z the third CSI-RS symbol carried over transmission beamC and measure one SNR for beam pair CZ accordingly, and the UE mayfinally attempt to receive over reception beam W the fourth CSI-RSsymbol carried over transmission beam D and measure one SNR for beampair DW accordingly. Afterwards, the UE may report the SNR measurementresults to the base station, and the base station may then considerthese measurement results when refining beams for subsequenttransmissions over PDSCH or receptions over PUSCH.

However, here, since the sequence of transmission beams A-B-C-D is fixed(e.g., it may be a pre-configured sequence agreed upon between the basestation and UE), and if the base station expects the UE to only performone measurement per symbol, the base station does not convey anyinformation to the UE regarding this sequence of transmission beamsduring transmission of the CSI-RS symbols 602. In contrast, if the UEindicates to the base station that the UE is capable of performingmultiple measurements per symbol (e.g., in a capability report), thebase station may determine a different sequence of transmission beamsand convey information regarding the determined sequence to the UEduring transmission of the CSI-RS symbols.

FIGS. 7A and 7B illustrate examples 700, 750 of CSI-RS symbols 702, 752that a base station may transmit to a UE when the UE is capable ofperforming four simultaneous RF measurements during a symbol length,assuming the UE has reported AX, BY, CZ, and DW as the best Ldistinguishable beam pairs as described above. While this examplespecifically refers to CSI-RS from a base station to a UE, similarprinciples may apply for SRS from a UE to a base station, or for CSI-RSor SRS between other wireless devices (e.g., side link or IAB devices).In example 700 of FIG. 7A, the base station may arbitrarily determinethe sequence of transmission beams to be C-B-D-A. In such cases, sincethe UE is capable of performing four measurements per symbol, the basestation may transmit M=4 CSI-RS symbols to the UE over transmissionbeams C, B, D, and A, respectively, in that order. Similarly, in example750 of FIG. 7B, the base station may arbitrarily determine the sequenceof transmission beams to be A-D-C-B. In such cases, since the UE iscapable of performing four measurements per symbol, the base station maytransmit M=4 CSI-RS symbols to the UE over transmission beams A, D, C,and B, respectively, in that order. In either example, the UE mayattempt to receive each CSI-RS symbol 702, 752 simultaneously overreception beams X, Y, Z, and W, estimate multiple RSRPs for each CSI-RSsymbol, and report measurement results accordingly. For instance, asillustrated in example 700, the UE may attempt to receive simultaneouslyover reception beams X, Y, Z, and W (using multiple RF chains or othercapability described above) the first CSI-RS symbol carried overtransmission beam C and measure four SNRs respectively for beam pairsCX, CY, CZ, CW accordingly, the UE may next attempt to receivesimultaneously over reception beams X, Y, Z, and W the second CSI-RSsymbol carried over transmission beam B and measure four SNRs for beampairs BX, BY, BZ, BW accordingly, and so forth. Similarly, asillustrated in example 750, the UE may attempt to receive simultaneouslyover reception beams X, Y, Z, and W the first CSI-RS symbol carried overtransmission beam A and measure four SNRs respectively for beam pairsAX, AY, AZ, AW accordingly, the UE may next attempt to receivesimultaneously over reception beams X, Y, Z, and W the second CSI-RSsymbol carried over transmission beam D and measure four SNRs for beampairs DX, DY, DZ, DW accordingly, and so forth. Afterwards, the UE mayreport the SNR measurement results to the base station, and the basestation may then consider these measurement results when refining beamsfor subsequent transmissions over PDSCH or receptions over PUSCH.

As described above, a transmitting device may determine a transmissionbeam sequence from the transmission beams in the distinguishable beampairs. For instance, assuming the UE has reported AX, BY, CZ, and DW asdistinguishable beam pairs, the base station may arbitrarily determinethe permutation of transmission beams to be C-B-D-A as in example 700,the permutation of transmission beams to be A-D-C-B as in example 750,or some other permutation from the set of transmission beam candidates{A, B, C, D} in the distinguishable beam pairs. Thus, the determinedsequence of transmission beams may depend on the number of transmissionbeam candidates L. Moreover, the number M of reference signal symbolsthat the transmitting device may send depends on the number oftransmission beam candidates as well as the number of measurements persymbol which the UE is capable of performing. For instance, in theexamples of FIGS. 7A and 7B, the base station may send M=4 CSI-RSsymbols across four transmission beams A, B, C, D when the UE is capableof performing four RF measurements in each symbol, while in otherexamples with four transmission beams A, B, C, D, the number of CSI-RSsymbols may increase to M=6 if the UE is capable of performing only twoRF measurements in each symbol or even further to M=16 if the UE iscapable of performing only one RF measurement in each symbol.

The transmitting device may impliedly convey information regarding thedetermined sequence of transmission beams, as described in more detailbelow with respect to FIGS. 8-11, over the number M of reference signalsymbols. The achievable rate at which this information may be conveyedis in bits per channel use (bpcu) and may be defined, for example, bythe following formula, where L represents a number of transmission beamcandidates and M represents a number of reference signal symbols:

$\begin{matrix}\left\{ \begin{matrix}\begin{matrix}{\frac{1}{M}{\log_{2}\left( \frac{L!}{L - M^{1}} \right)}\ } & {{{if}\ L} \geq M}\end{matrix} \\\begin{matrix}{\frac{1}{M}{\log_{2}\left( {L!} \right)}\ } & {{{if}\ L} < M}\end{matrix}\end{matrix} \right. & (1)\end{matrix}$

Similarly, the number of reception beams which the receiving device maysearch during beam refinement (i.e., the number of reception beams overwhich the UE or other receiving device performs SNR measurements) maydepend on the number of transmission beam candidates L and the number Mof reference signal symbols as defined, for example, by the followingformula:

$\begin{matrix}\left\{ \begin{matrix}\begin{matrix}{\frac{L\left( {L + 1} \right)}{2} - \frac{\left( {L - M} \right)\left( {L - M + 1} \right)}{2}\ } & {{{if}\ L} \geq M}\end{matrix} \\\begin{matrix}{\frac{L\left( {L + 1} \right)}{2}\ } & {{{if}\ L} < M}\end{matrix}\end{matrix} \right. & (2)\end{matrix}$

As the value of L increases, the achievable rate (in bpcu) and thenumber of reception beams to be searched can be approximated as log₂ Land LM, respectively.

FIG. 8 illustrates an example 800 of a chart showing a relationshipbetween the achievable rate and number of reception beams to be searchedfor different values of L=2, 4, 6, 8, 10, 12, 14, 16 when M=8. As can beseen in the chart, as the achievable rate increases (as more informationregarding transmission beam sequences is conveyed) and as the number oftransmission beam candidates 802 increases, the number of receptionbeams to be searched also increases in a linearly growing trend. Thus, atradeoff may exist between search time (latency) and achievable rate.

For example, referring to FIGS. 7A and 7B, if a base station sends M=4CSI-RS symbols respectively over L=4 transmission beams and if the UE iscapable of performing four RF measurements during a symbol length, theachievable rate at which the base station conveys information regardingthe transmission beam sequence (e.g. C-B-D-A or A-D-C-B) over the fourCSI-RS symbols is 1.15 bpcu

$\left( {{i.e.},\ {\log_{2}\frac{4!}{4}}} \right).$

Alternatively, it the UE is only capable of performing two RFmeasurements during a symbol length, the base station sends M=6 CSI-RSsymbols to allow the UE to perform measurements over all L=4transmission beams, leading to an achievable rate of 0.76 bpcu

$\left( {{i.e.},\ {\log_{2}\frac{4!}{6}}} \right).$

This example is illustrated in FIG. 9 described below. In contrast, ifthe UE is only capable of performing one RF measurement during a symbollength, the base station sends M=16 CSI-RS symbols to allow the UE toperform measurements over all L=4 transmission beams, leading to anachievable rate of 0.29 bpcu

$\left( {{i.e.},\ {\log_{2}\frac{4!}{16}}} \right)$

Thus, in cases where a transmitting device does not change itstransmission beam across RF chains during a symbol length, but where areception device may perform two RF measurements (over two receptionbeams) per symbol, the receiving device may determine the transmissionbeam sequence at a faster rate (e.g., a faster rate of 0.76 bpcu) thanif the receiving device is only capable of performing one RF measurementper symbol (e.g., a slower rate of 0.29 bpcu).

FIG. 9 illustrates an example 900 of CSI-RS symbols 902 that a basestation may transmit to a UE over four transmission beams A, B, C, andD. The example illustrates how the base station may impliedly convey atransmission beam sequence to a UE capable of performing 2 RFmeasurements per CSI-RS symbol (i.e., measuring SNRs over two receptionbeams during a symbol length). While this example specifically refers toCSI-RS from a base station to a UE, similar principles may apply for SRSfrom a UE to a base station, or for CSI-RS or SRS between other wirelessdevices. For instance, the UE may similarly implicitly convey atransmission beam sequence to a base station capable of performing 2 RFmeasurements per SRS symbol.

In this example 900, based on the number of transmission beams and theRF measurement capability of the UE, the base station may determine totransmit M=6 CSI-RS symbols over various transmission beams in thefollowing arbitrarily determined sequence: A-B-C-D. The base station maydetermine the sequence from the list of transmission beam candidates inthe set of distinguished beam pairs AX, BY, CZ, and DW, which the basestation has previously received from the UE. The UE may determine thetransmission beam sequence as a result of its reception beammeasurements as the UE receives the CSI-RS symbols 902. For example, theUE may determine the sequence of transmission beams in response tomeasuring SNRs over four reception beams X, Y, Z, and W. In thisexample, the SNRs associated with each transmission-reception beam pair(e.g., AX, AY, AZ, AW, BX, BY, BZ, BW, etc.) may match the SNRsillustrated in the example of FIG. 5.

In the illustrated example, the base station has determined the UE iscapable of performing two RF measurements per symbol, e.g., in responseto a capability report from the UE. Therefore, the base station mayinitially transmit the first two CSI-RS symbols over transmission beam A(the first beam in the sequence) for the UE to measure across all of itsreception beams X, Y, Z, W. Thus, the UE may simultaneously measure SNRsover reception beams X and Y during the first CSI-RS symbol and overreception beams Z and W during the second CSI-RS symbol, although the UEmay select different reception beams for each symbol in other examples.Here, the UE may determine that reception beam X is the best beam sinceit is associated with the highest SNR (e.g., as illustrated in FIG. 5),and the UE may compare reception beam X with the distinguishable beampairs. Upon determining that X is paired with A in the set ofdistinguishable beam pairs, the UE may determine at 904 that the firstand second CSI-RS symbols were transmitted over transmission beam A.Thus, the UE may determine that the transmission beam sequence beginswith A. Additionally, as the base station does not transmit sequenceswith duplicate or missing transmission beams (e.g., A-A-C-D, A-B-C-B,D-C-B-D, etc.), the UE may determine that transmission beam A will notbe used for the remaining CSI-RS symbols, and therefore the UE mayeliminate reception beam X from its subsequent measurements.

Subsequently, the base station may transmit the next two CSI-RS symbolsover transmission beam B (the second beam in the sequence) for the UE tomeasure across all its remaining reception beams Y, Z, W. Thus, in theillustrated example, the UE may simultaneously measure SNRs overreception beams Y and Z during the third CSI-RS symbol and overreception beam W during the fourth CSI-RS symbol. Alternatively, the UEmay measure reception beams Y, Z, and W in a different order thanillustrated across the third and fourth CSI-RS symbols. Here, the UE maydetermine that reception beam Y is the best beam since it is associatedwith the highest SNR (e.g., as illustrated in FIG. 5), and the UE maycompare reception beam Y with the distinguishable beam pairs. Upondetermining that Y is paired with B in the set of distinguishable beampairs, the UE may determine at 906 that the third and fourth CSI-RSsymbols were transmitted over transmission beam B. Thus, the UE maydetermine that the transmission beam sequence continues with B.Additionally, as the base station does not transmit sequences withduplicate or missing transmission beams, the UE may determine thattransmission beam B will not be used for the remaining CSI-RS symbols,and therefore the UE may eliminate reception beam Y from its subsequentmeasurements.

Next, the base station may transmit a CSI-RS symbol over transmissionbeam C (the third beam in the sequence) for the UE to measure across itsremaining reception beams Z and W. Thus, the UE may simultaneouslymeasure SNRs over reception beams Z and W during the fifth CSI-RSsymbol. Here, the UE may determine that reception beam Z is the bestbeam since it is associated with the highest SNR (e.g., as illustratedin FIG. 5), and the UE may compare reception beam Z with thedistinguished beam pairs. Upon determining that Z is paired with C inthe set of distinguished beam pairs, the UE may determine at 908 thatthe fifth CSI-RS symbol was transmitted over transmission beam C. Thus,the UE may determine that the transmission beam sequence continues withC. Additionally, as the base station does not transmit sequences withduplicate or missing transmission beams, the UE may determine thattransmission beam C will not be used for the remaining CSI-RS symbol,and therefore the UE may eliminate reception beam Z from its subsequentmeasurements.

Finally, the base station may transmit a CSI-RS symbol over transmissionbeam D (the fourth beam in the sequence) for the UE to measure over itsremaining reception beam W. Even though one reception beam remains, theUE may still measure SNR to determine beam link quality. Thus, the UEmay measure the SNR over reception beam W during the sixth CSI-RS symbolto determine if W is still the best beam. The UE may then comparereception beam W with the distinguished beam pairs. Upon determiningthat W is paired with D in the set of distinguished beam pairs, the UEmay determine at 910 that the sixth CSI-RS symbol was transmitted overtransmission beam D. Thus, the UE may determine that the transmissionbeam sequence finishes with D, and therefore that the entiretransmission beam sequence was A-B-C-D. In this way, through the UE'sidentification of reception beams that best receive each CSI-RS symbolas described above, the base station may impliedly convey thetransmission beam sequence A-B-C-D to the UE.

In another example, the transmitting device (e.g., a base station, UE,or other wireless device) may group transmission beams into differentbeam groups. For example, the base station may arbitrarily grouptransmission beams A, B, C, D such that one group includes transmissionbeams A and D (Group 1={A, D}), and the other group includestransmission beams B and C (Group 2={B, C}). The transmitting device maygroup the transmission beams differently in other examples. Afterconfiguring the transmission beam groups, the transmitting device mayprovide the groupings to the receiving device (e.g., a UE, a basestation, or other wireless device). For example, the base station mayindicate to the UE that Group 1={A, D} and Group 2={B, C}. Subsequently,when the transmitting device determines a transmission beam sequenceduring beam management, the transmitting device first determines whichgroup of transmission beams will be sent initially. For instance, thebase station may randomly select to transmit beams initially in thefirst group {A, D} followed by the beams in the second group {B, C}.After selecting the group order, the transmitting device proceeds toselect the beam order within each group to obtain the transmission beamsequence. For instance, in the first group, the base station mayarbitrarily select transmission beam D followed by transmission beam A,and then in the second group, the base station may arbitrarily selecttransmission beam C followed by transmission beam B. Thus, in thisexample, the transmitting device may determine the sequence oftransmission beams to be D-A-C-B based on randomly selected transmissionbeam groups.

Transmission beam grouping may result in more transmission beamcandidates (a higher L) than in the example of FIG. 9. For instance, ifthe base station groups four transmission beams into two groups asdescribed above, then when determining the transmission beam sequence,the base station may select between two groups, between two beams in thefirst group, and between two beams in the second group (L=8=2*2*2),rather than between four beams in one group as in the prior example(L=4). Moreover, the grouping may result in less number of CSI-RSsymbols (a lower M) than in the example of FIG. 9. For instance, if thebase station groups four transmission beams into two groups and the UEis capable of performing two RF measurements per symbol, the basestation may transmit M=5 CSI-RS symbols (rather than M=6 CSI-RS symbolsas in the prior example) since the UE may be able to eliminate certainreception beams for CSI-RS symbols corresponding to differenttransmission beam groups. This example can be seen as described belowwith respect to FIG. 10. Thus, transmission beam grouping in thisexample (where L=8 and M=5) may lead to an achievable rage of 0.6 bpcu

$\left( {{i.e.},{\log_{2}\frac{8!}{5}}} \right)$

Although transmission beam grouping may accordingly lead to smallerrates than may be achieved without such grouping (e.g., 0.6 bpcu issmaller than the achievable rate of 0.76 bpcu in the prior example ofFIG. 9), such grouping may allow the UE to perform more uniform RFmeasurements across all CSI-RS symbols. For instance, with transmissionbeam grouping, the UE may uniformly perform two SNR measurements duringall five CSI-RS symbols to identify the transmission beam sequence,rather than non-uniformly perform one or two SNR measurements duringeach CSI-RS symbol as illustrated in the example of FIG. 9.

FIG. 10 illustrates an example 1000 of CSI-RS symbols 1002 that a basestation may transmit to a UE over four transmission beams A, B, C, and Din different transmission beam groups 1004. The example illustrates howthe base station may impliedly convey a transmission beam sequence to aUE capable of performing 2 RF measurements per CSI-RS symbol (i.e.,measuring SNRs over two reception beams during a symbol length) when thetransmission beams in the sequence are in different transmission beamgroups. While this example specifically refers to CSI-RS from a basestation to a UE, similar principles may apply for SRS from a UE to abase station, or for CSI-RS or SRS between other wireless devices. Forinstance, the UE may similarly impliedly convey a transmission beamsequence to a base station capable of performing 2 RF measurements perSRS symbol when the transmission beams in the sequence are in differenttransmission beam groups.

In example 1000, based on the number of transmission beams and the RFmeasurement capability of the UE, the base station may determine totransmit M=5 CSI-RS symbols over various transmission beams in thefollowing arbitrarily determined sequence: D-A-C-B. The base station maydetermine the sequence (e.g., the group order and beam order within eachgroup) from the list of transmission beam candidates in the set ofdistinguished beam pairs AX, BY, CZ, and DW, which the base station haspreviously received from the UE. The UE may determine the transmissionbeam sequence as a result of its reception beam measurements as the UEreceives the CSI-RS symbols 1002. For example, the UE may determine thesequence of transmission beams in response to measuring SNRs over fourreception beams X, Y, Z, and W. In this example, the SNRs associatedwith each transmission-reception beam pair (e.g., AX, AY, AZ, AW, BX,BY, BZ, BW, etc.) may match the SNRs illustrated in the example of FIG.5.

In the illustrated example, the base station has determined the UE iscapable of performing two RF measurements per symbol, e.g., in responseto a capability report from the UE. Therefore, the base station mayinitially transmit the first two CSI-RS symbols over transmission beam D(the first beam in the sequence and the initial beam in Group 1) for theUE to measure across all of its reception beams X, Y, Z, W. Thus, the UEmay simultaneously measure SNRs over reception beams X and W during thefirst CSI-RS symbol and over reception beams Y and Z during the secondCSI-RS symbol, although the UE may select different reception beams foreach symbol in other examples. Here, the UE may determine that receptionbeam W is the best beam since it is associated with the highest SNR(e.g., as illustrated in FIG. 5), and the UE may compare reception beamW with the distinguishable beam pairs. Upon determining that W is pairedwith D in the set of distinguishable beam pairs, the UE may determine at1006 that the first and second CSI-RS symbols were transmitted overtransmission beam D. Thus, the UE may determine that the transmissionbeam sequence begins with D, and therefore that the base station hasselected to initially proceed with Group 1={A, D}. Additionally, as thebase station transmits over all transmission beams in a selected groupbefore moving on to the next group, the UE may eliminate pairedreception beams outside of the selected group for its subsequentmeasurement(s). For example, upon determining the base station hasselected Group 1={A, D}, the UE may determine that transmission beams Band C will not be used for the next CSI-RS symbol since those beams arenot in Group 1. Therefore the UE may only proceed with paired receptionbeams X and W in its subsequent measurement, since those beams arepaired with the Group 1 beams in the set of distinguishable beam pairs.

Subsequently, the base station may transmit the next CSI-RS symbol overtransmission beam A (the second beam in the sequence and the next beamin Group 1) for the UE to measure across reception beams X and W. Eventhough the UE may ascertain the transmission beam is A at this time, theUE may still measure the SNRs of X and W to determine beam link quality.Thus, in the illustrated example, the UE may simultaneously measure SNRsover reception beams X and W during the second CSI-RS symbol. Here, theUE may determine that reception beam X is the best beam since it isassociated with the highest SNR (e.g., as illustrated in FIG. 5), andthe UE may compare reception beam X with the distinguishable beam pairs.Upon determining that X is paired with A in the set of distinguishablebeam pairs, the UE may determine at 1008 that the second CSI-RS symbolwas transmitted over transmission beam A. Thus, the UE may determinethat the transmission beam sequence continues with A. Additionally, asthe base station has transmitted over all transmission beams in Group 1,the UE may determine that the base station will proceed with thetransmission beams in Group 2, and therefore the UE may eliminate pairedreception beams in Group 1 for its subsequent measurements. For example,the UE may determine that transmission beams B and C will now be usedfor the next CSI-RS symbols since those beams are in Group 2. Thereforethe UE may only proceed with paired reception beams Y and Z in itssubsequent measurement, since those beams are paired with the Group 2beams in the set of distinguishable beam pairs.

Next, the base station may transmit a CSI-RS symbol over transmissionbeam C (the third beam in the sequence and the initial beam in Group 2)for the UE to measure across reception beams Y and Z. Thus, the UE maysimultaneously measure SNRs over reception beams Y and Z during thefourth CSI-RS symbol. Here, the UE may determine that reception beam Zis the best beam since it is associated with the highest SNR (e.g., asillustrated in FIG. 5), and the UE may compare reception beam Z with thedistinguishable beam pairs. Upon determining that Z is paired with C inthe set of distinguishable beam pairs, the UE may determine at 1010 thatthe fourth CSI-RS symbol was transmitted over transmission beam C. Thus,the UE may determine that the transmission beam sequence continues withC. Additionally, as the base station transmits over all transmissionbeams in a selected group, the UE may continue to measure over pairedreception beams in the selected group for its subsequent measurement(s).For example, upon determining the base station has selected Group 2 {B,C}, the UE may determine that transmission beams A and D will not beused for the next CSI-RS symbol since those beams are not in Group 2.Therefore, the UE may continue to measure with paired reception beams Yand Z in its subsequent measurement, since those beams are paired withthe Group 2 beams in the set of distinguishable beam pairs.

Finally, the base station may transmit a CSI-RS symbol over transmissionbeam B (the fourth beam in the sequence and the next beam in Group 2)for the UE to measure across reception beams Y and Z. Even though the UEmay ascertain the transmission beam is B at this time, the UE may stillmeasure the SNRs of Y and Z to determine beam link quality. Thus, the UEmay simultaneously measure SNRs over reception beams Y and Z during thefifth CSI-RS symbol. Here, the UE may determine that reception beam Y isthe best beam since it is associated with the highest SNR (e.g., asillustrated in FIG. 5), and the UE may compare reception beam Y with thedistinguished beam pairs. Upon determining that Y is paired with B inthe set of distinguished beam pairs, the UE may determine at 1012 thatthe fifth CSI-RS symbol was transmitted over transmission beam B. Thus,the UE may determine that the transmission beam sequence finishes withB, and therefore that the entire transmission beam sequence was D-A-C-B.In this way, through the UE's identification of reception beams thatbest receive each CSI-RS symbol as described above, the base station mayimpliedly convey the transmission beam sequence D-A-C-B to the UE.

Furthermore, in some cases, the best beam pairs that the UE and basestation may identify during beam training may include transmission beamswhich are not associated with distinguishable reception beams. Forexample, assume that during beam training, the UE identifies and reportsthe best K beam pairs as AX, BX, CZ, and DW. Here, transmission beams Aand B are both associated with the same reception beam X, and thereforeX is not a distinguishable reception beam. This concept ofdistinguishable reception beams is different than the concept ofdistinguishable beam pairs as described above with respect to FIG. 5.For example, even though AX may not include a distinguishable receptionbeam, AX may still be a distinguishable beam pair if the differencebetween its SNR and the maximum SNR of AY, AZ, and AW meets a signalstrength threshold.

In such case of distinguishable reception beams, when the transmittingdevice (e.g., the base station, the UE, or other wireless device)performs transmission beam grouping of transmission beams as describedabove, the transmitting device may group the transmission beams suchthat transmission beams associated with indistinguishable receptionbeams are placed in different groups. For example, the base station mayselect the groups such that Group 1={A, D} and Group 2={B, C}, similarto that described above in the example of FIG. 10, to ensure thattransmission beams A and B are in different transmission beam groups andthus are pairwise distinguishable within each group. The transmittingdevice may then arbitrarily determine the transmission beam sequencebased on transmission beam groups as described above, e.g., by randomlyselecting the group order followed by the beam order for each group.Thus, similar to the example of FIG. 10, here L=8 since there again maybe eight different possibilities of beam combinations, namely twobetween Group 1 and Group 2, two between the beams in Group 1, and twobetween the beams in Group 2. However, unlike the example of FIG. 10where the base station may transmit M=5 CSI-RS symbols, in this examplethe presence of indistinguishable reception beams may cause the basestation to transmit M=6 CSI-RS symbols to allow the UE to determine thetransmission beam sequence. Thus, indistinguishable reception beams intransmission beam groups may lead to a smaller achievable rate of 0.5bpcu

$\left( {{i.e.},{\log_{2}\frac{8!}{6}}} \right)$

than in the prior example of FIG. 10.

FIG. 11 illustrates an example 1100 of CSI-RS symbols 1102 that a basestation may transmit to a UE over four transmission beams A, B, C, and Din different transmission beam groups 1104, where transmission beamsassociated with indistinguishable reception beams are separated amongthe groups. The example illustrates how the base station may impliedlyconvey a transmission beam sequence to a UE capable of performing 2 RFmeasurements per CSI-RS symbol (i.e., measuring SNRs over two receptionbeams during a symbol length) when the transmission beams in thesequence are in different transmission beam groups and associated withindistinguishable reception beams. While this example specificallyrefers to CSI-RS from a base station to a UE, similar principles mayapply for SRS from a UE to a base station, or for CSI-RS or SRS betweenother wireless devices. For instance, the UE may similarly impliedlyconvey a transmission beam sequence to a base station capable ofperforming 2 RF measurements per SRS symbol when the transmission beamsin the sequence are in different transmission beam groups and associatedwith indistinguishable reception beams.

In example 1100, based on the number of transmission beams and the RFmeasurement capability of the UE, the base station may determine totransmit M=6 CSI-RS symbols over various transmission beams in thefollowing arbitrarily determined sequence: A-D-C-B. The base station maydetermine the sequence (e.g., the group order and beam order within eachgroup) from the list of transmission beam candidates in the set ofdistinguished beam pairs AX, BX, CZ, and DW, which the base station haspreviously received from the UE. The UE may determine the transmissionbeam sequence as a result of its reception beam measurements as the UEreceives the CSI-RS symbols 1102. For example, the UE may determine thesequence of transmission beams in response to measuring SNRs over threereception beams X, Z, and W. In this example, the SNRs associated witheach transmission-reception beam pair (e.g., AX, AZ, AW, BX, BZ, BW,etc.) may match the SNRs illustrated in the example of FIG. 5.

In the illustrated example, the base station has determined the UE iscapable of performing two RF measurements per symbol, e.g., in responseto a capability report from the UE. Therefore, the base station mayinitially transmit the first two CSI-RS symbols over transmission beam A(the first beam in the sequence and the initial beam in Group 1) for theUE to measure across all of its reception beams X, Z, W. Thus, the UEmay simultaneously measure SNRs over reception beams X and W during thefirst CSI-RS symbol and over reception beams X and Z during the secondCSI-RS symbol, although the UE may select different reception beams foreach symbol in other examples. Here, the UE may determine that receptionbeam X is the best beam since it is associated with the highest SNR(e.g., as illustrated in FIG. 5), and the UE may compare reception beamX with the distinguishable beam pairs. Upon determining that X is pairedwith both A and B in the set of distinguishable beam pairs, the UE maybe unable to determine at 1106 whether the first and second CSI-RSsymbols were transmitted over transmission beam A or over transmissionbeam B, since both beams are in different transmission beam groups andthe UE has not yet identified which group was initially selected by thebase station. Thus, the UE will proceed to measure the next CSI-RSsymbols again over reception beams X, W and Z.

Subsequently, the base station may transmit the next two CSI-RS symbolsover transmission beam D (the second beam in the sequence and the nextbeam in Group 1) for the UE to measure across all of its reception beamsX, Z and W. Thus, in the illustrated example, the UE may simultaneouslymeasure SNRs over reception beams X and W during the third CSI-RS symboland over reception beams X and Z during the fourth CSI-RS symbol,although the UE may select different reception beams for each symbol inother examples. Here, the UE may determine that reception beam W is thebest beam since it is associated with the highest SNR (e.g., asillustrated in FIG. 5), and the UE may compare reception beam W with thedistinguishable beam pairs. Upon determining that W is paired with D inthe set of distinguishable beam pairs, the UE may determine at 1108 thatthe third and fourth CSI-RS symbols were transmitted over transmissionbeam D. Additionally, the UE may determine that since the base stationtransmits over all transmission beams in a group before moving on to thenext group, the UE may ascertain that the first and second CSI-RSsymbols were transmitted over transmission beam A (since Group 1={A,D}). Thus, the UE may determine that the transmission beam sequencestarts with A-D. Additionally, as the base station has transmitted overall transmission beams in Group 1, the UE may determine that the basestation will proceed with the transmission beams in Group 2, andtherefore the UE may eliminate paired reception beams in Group 1 for itssubsequent measurements. For example, the UE may determine thattransmission beams B and C will now be used for the next CSI-RS symbolssince those beams are in Group 2. Therefore the UE may only proceed withpaired reception beams X and Z in its subsequent measurements, sincethose beams are paired with the Group 2 beams in the set ofdistinguishable beam pairs.

Next, the base station may transmit a CSI-RS symbol over transmissionbeam C (the third beam in the sequence and the initial beam in Group 2)for the UE to measure across reception beams X and Z. Thus, the UE maysimultaneously measure SNRs over reception beams X and Z during thefifth CSI-RS symbol. Here, the UE may determine that reception beam Z isthe best beam since it is associated with the highest SNR (e.g., asillustrated in FIG. 5), and the UE may compare reception beam Z with thedistinguishable beam pairs. Upon determining that Z is paired with C inthe set of distinguishable beam pairs, the UE may determine at 1110 thatthe fifth CSI-RS symbol was transmitted over transmission beam C. Thus,the UE may determine that the transmission beam sequence continues withC. Additionally, as the base station transmits over all transmissionbeams in a selected group, the UE may continue to measure over pairedreception beams in the selected group for its subsequent measurement(s).For example, upon determining the base station has selected Group 2 {B,C}, the UE may determine that transmission beams A and D will not beused for the next CSI-RS symbol since those beams are not in Group 2.Therefore the UE may continue to measure with paired reception beams Xand Z in its subsequent measurement, since those beams are paired withthe Group 2 beams in the set of distinguishable beam pairs.

Finally, the base station may transmit a CSI-RS symbol over transmissionbeam B (the fourth beam in the sequence and the next beam in Group 2)for the UE to measure across reception beams X and Z. Even though the UEmay ascertain the transmission beam is B at this time, the UE may stillmeasure the SNRs of X and Z to determine beam link quality. Thus, the UEmay simultaneously measure SNRs over reception beams X and Z during thesixth CSI-RS symbol. Here, the UE may determine that reception beam X isthe best beam since it is associated with the highest SNR (e.g., asillustrated in FIG. 5), and the UE may compare reception beam X with thedistinguished beam pairs. Upon determining that X is paired with A and Bin the set of distinguished beam pairs and that the current group isGroup 2 {B, C}, the UE may determine at 1112 that the sixth CSI-RSsymbol was transmitted over transmission beam B. Thus, the UE maydetermine that the transmission beam sequence finishes with B, andtherefore that the entire transmission beam sequence was A-D-C-B. Inthis way, through the UE's identification of reception beams that bestreceive each CSI-RS symbol as described above, the base station mayimpliedly convey the transmission beam sequence A-D-C-B to the UE.

The base station may determine whether to impliedly convey a determinedtransmission beam sequence (such as described above with respect toFIGS. 9-11), or whether to merely transmit CSI-RS symbols according to afixed transmission beam sequence without conveying information regardingthe sequence (such as described above with respect to FIG. 6), inresponse to a capability information message from the UE. The capabilityinformation message may indicate whether the UE has hardware capabilityto perform multiple, simultaneous RF measurements during a symbollength, or the number of possible measurements the UE may perform duringa symbol length or other defined period of time. In response to thecapability information message, the base station may determine thenumber M of CSI-RS symbols to transmit according to its determinedtransmission beam sequence as previously described.

Moreover, the base station as transmitting device and UE as receivingdevice (or vice-versa) may determine the sequence of transmission beamsbased on the distinguishable beam pair set as described above. Forinstance, the base station may identify candidates to select for itstransmission beam sequence from the distinguishable beam pair set, andthe UE may determine the sequence of transmission beams selected by thebase station in response to identifying the best reception beams fromthe distinguishable beam pair set. As described above, the UE maydetermine the distinguishable beam pairs based on a signal strengththreshold configured by the base station, and the UE may identifydistinguishable beam pairs in response to searching for the bestreception beams over multiple RF measurements per CSI-RS symbol carriedover each associated transmission beam. Moreover, since distinguishablebeam pairs may change with channel conditions (e.g., in response to usermobility, change in channel environment, blockage conditions, etc.), theUE may constantly update and report the set of distinguishable beampairs.

Additionally, the base station as transmitting device may inform the UEas receiving device (or vice-versa) whether any groups of transmissionbeams are present, including the number of transmission beam groups andthe transmission beams which constitute each group. If the UE indicatesto the base station that any of the transmission beams are associatedwith indistinguishable reception beams (e.g., in the set ofdistinguishable beam pairs), the base station may group the transmissionbeams accordingly as described above with respect to FIG. 11.

While the examples described above with respect to FIGS. 6, 7A-7B, and9-11 all refer to a base station determining a sequence of transmissionbeams, the base station sending CSI-RS symbols over each transmissionbeam to the UE, the UE performing multiple RF measurements during eachCSI-RS symbol to identify the best reception beams, and the UEsubsequently determining the transmission beam sequence which the basestation impliedly conveys, the examples are not so limited. For example,the roles of the base station and UE may be reversed, in which case theUE may arbitrarily determine a sequence of transmission beams, the UEmay send SRS symbols over each transmission beam to the UE, the basestation may perform multiple RF measurements (e.g., based on multiple RFchains or other aforementioned capability) during each SRS symbol toidentify the best reception beams, and the base station may subsequentlydetermine the transmission beam sequence which the UE impliedly conveys.Thus, the transmitting device and receiving device described abovethroughout this disclosure are not limited to a base station and a UE,respectively, but may include other devices. For example, either thetransmitting device or receiving device may be a base station, a TRP, arepeater, an IAB node, a UE, a relay or sidelink node, or a CPE.

FIG. 12 is an example 1200 of a call flow between a wireless device 1202and a wireless device 1204. Wireless device 1202 may be, for example, aUE, a relay or sidelink node, a CPE, a repeater, or an JAB node, whichincludes multiple antennas that may transmit or receive data over anygiven carrier frequency. Wireless device 1204 may be, for example, abase station, a TRP, a UE, a relay or sidelink node, a CPE, a repeater,or an JAB node, which includes multiple antennas that may transmit orreceive data over any given carrier frequency. For clarity ofexplanation, the following example description refers to wireless device1202 as a UE and wireless device 1204 as a base station, although thewireless devices 1202, 1204 may be different devices in other examples.

The UE initially provides a capability report 1206 to the base station(e.g., in response to a capability inquiry message from the basestation). In one example, the capability report 1206 may indicate acapability of the UE to perform multiple RF measurements during a symbollength. For example, the capability report may include a bit or otherflag indicating whether the UE may perform two or more measurements (orreception beam switches) during a CSI-RS symbol. The capability report1206 may alternatively (or additionally) indicate a number ofmeasurements which the UE may perform during a CSI-RS symbol. Forexample, the UE may indicate to the base station that the UE may performtwo, four, or other number of measurements (or reception beam switches)during a CSI-RS symbol such as described above with respect to FIGS.7A-7B and 9-11. The capability report 1206 may alternatively (oradditionally) indicate a maximum number of reception beam switches theUE may perform in a defined (e.g., a preconfigured) time period. Forexample, the UE may indicate to the base station that the UE may performten measurements in total over a preconfigured time period of sixsymbols, such as illustrated in FIG. 9, or over five symbols, such asillustrated in FIG. 10.

In response to the capability report 1206, the base station may providea message 1208 indicating a beam sequence conveyance mode. The beamsequence conveyance mode may indicate to the UE whether the base stationwill impliedly convey an arbitrarily determined sequence of transmissionbeams during beam management, such as described above with respect toFIGS. 9-11, or whether the base station will merely transmit CSI-RSsymbols according to a fixed transmission beam sequence during beammanagement (e.g., a pre-configured sequence previously agreed betweenthe base station and UE or some other fixed sequence), such as describedabove with respect to FIG. 6. For example, the beam sequence conveyancemode may be in the form of a bit or flag which value indicates to the UEwhether the base station will arbitrarily determine a transmission beamsequence for beam management, or whether the base station will performconventional beam management procedures according to a fixed sequence oftransmission beams. The base station may select the value or otherwisechange to the beam sequence conveyance mode in response to determiningfrom the capability report 1206 that the UE is capable of performingmultiple RF measurements during a symbol length.

The base station may also provide a signal strength threshold 1210(e.g., SNR_(threshold)) to the UE, and the UE may determine and providea set of distinguishable beam pairs 1212 to the base station based onthe signal strength threshold. For example, as described above withrespect to FIG. 5, after the base station has transmitted SSBs acrossfour transmission beams A, B, C, D, and the UE has received each SSBover four reception beams X, Y, Z, W, the UE may measure the SNRs 504 ofsixteen beam pairs AX, AY, AZ, AW, BX, BY, BZ, BW, CX, CY, CZ, CW, DX,DY, DZ, DW and determine that AX, BY, CZ, and DW are the K best beampairs respectively for each transmission beam. If the UE determines theSNR_(threshold)=7 dB, the UE may also determine that all of these bestbeam pairs are distinguishable beam pairs, since the difference betweenthe SNR of AX and the maximum SNR of (AY, AZ, AW), the differencebetween the SNR of BY and the maximum SNR of (BX, BZ, BW), thedifference between the SNR of CZ and the maximum SNR of (CX, CY, CW),and the difference between the SNR of DW and the maximum SNR of (DX, DY,DZ), are all equal to or larger than SNR_(threshold). Thus, the UE mayreport to the base station beam pairs AX, BY, CZ, and DW asdistinguishable beam pairs 1212 in response to receiving the signalstrength threshold 1210 (e.g., 7 dB). Alternatively, the signal strengththreshold 1210 may be a pre-configured threshold determinable by the UEwithout being provided expressly by the base station.

The base station may further provide a configuration 1214 oftransmission beam groups to the UE. For example, as described above withrespect to FIGS. 10 and 11, the base station may arbitrarily grouptransmission beams A, B, C, and D into two groups such that Group 1={A,D} and Group 2={B, C}, and the base station may indicate this groupingto the UE in the configuration. The configuration 1214 may indicate tothe UE whether any groups of transmission beams are present, includingthe number of transmission beam groups and the transmission beams whichconstitute each group. Moreover, if the UE indicates to the base stationthat any of the transmission beams are associated with indistinguishablereception beams (e.g., the base station identifies common receptionbeams in the set of distinguishable beam pairs 1212), the base stationmay separately group these transmission beams such as described abovewith respect to FIG. 11.

At 1216, the base station may determine a sequence of transmissionbeams. For example, the base station may determine the sequence oftransmission beams from the transmission beams indicated in thedistinguished beam pairs 1212. For instance, the base station mayarbitrarily determine a transmission beam sequence from one of multiplepermutations or combinations of transmission beam candidates identifiedin the distinguished beam pairs of FIG. 5 (e.g., transmission beams A,B, C, D), such as one of the sequences illustrated and described abovewith respect to FIGS. 7A-7B and 9-11 (e.g., C-B-D-A, A-D-C-B, A-B-C-D,D-A-C-B, etc.). Moreover, when transmission beam groups are configured(e.g., in configuration 1214), the base station may also determine agroup order and a beam order within each group when determining thesequence of transmission beams. For example, as described above withrespect to FIGS. 10 and 11, the base station may determine thetransmission beam sequence as a result of randomly selecting Group 1 orGroup 2, the beam order in the randomly selected group, and then thebeam order in the remaining group.

Afterwards, at 1218, the base station associates a CSI-RS 1220 with eachtransmission beam in the determined sequence at 1216. For example, asillustrated and described above with respect to FIGS. 7A-7B and 9-11,the base station may configure CSI-RS symbols 702, 752, 902, 1002, 1102for transmission over the various transmission beams in the determinedtransmission beam sequence. The number of CSI-RS symbols M may depend onthe number of transmission beam candidates in the distinguished beampairs 1212, the configuration 1214 of transmission beam groups ifpresent, and the presence if any of indistinguishable reception beams inthe distinguished beam pairs. The base station may then send the CSI-RS1220 to the UEs over the transmission beams in the determined sequence.For example, the base station may send the CSI-RS to the UE overassociated transmission beams for the UE to measure during beammanagement.

At 1222, the UE may identify a reception beam for each transmission beamcarrying the CSI-RS 1220. For example, as illustrated and describedabove with respect to FIGS. 9-11, the UE may identify a best receptionbeam (e.g., a reception beam associated with the highest SNR) forreceiving each CSI-RS over the transmission beams. In one example, at1224, the UE may perform a plurality of channel measurements of CSI-RSduring a symbol over different reception beams. For instance, asillustrated and described above with respect to FIG. 9, the UE maysimultaneously measure the SNRs over reception beams X and Y during thefirst CSI-RS symbol carried over transmission beam A, as well as theSNRs over reception beam Z and W during the second CSI-RS symbol alsocarried over transmission beam A. In such case, the UE may determinethat reception beam X is associated with the highest SNR. Thus, the UEmay identify reception beam X for the initial transmission beamscarrying the CSI-RS. Then, at 1226, the UE may identify adistinguishable beam pair for the CSI-RS. For instance, as illustratedand described above with respect to FIGS. 5 and 9, the UE may check theset of distinguishable beam pairs (e.g., distinguishable beam pairs1212) and determine that reception beam X is paired with transmissionbeam A. As a result, the UE may determine that the first and secondCSI-RS symbols were transmitted over transmission beam A, and thus thatthe transmission beam sequence determined at 1216 begins withtransmission beam A. Furthermore, at 1228, the UE may refrain fromperforming subsequent channel measurements with the distinguishable beampair. For instance, as illustrated and described above with respect toFIG. 9, the UE may determine that transmission beam A will not be usedfor the remaining CSI-RS symbols since the base station does nottransmit sequences with duplicate or missing transmission beams, and sothe UE may eliminate reception beam X from its subsequent measurements.As a result, when the base station transmits the next two CSI-RS symbolsover transmission beam B, the UE may only measure SNRs over receptionbeams Y, Z, and W (and not X). The UE may then repeat the aforementionedprocess over the remaining CSI-RS symbols, such as illustrated anddescribed above with respect to FIG. 9, to identify the other receptionbeams, including reception beam Y for the third and fourth CSI-RSsymbols carried over transmission beam B, reception beam Z for the fifthCSI-RS symbol carried over transmission beam C, and reception beam W forthe sixth CSI-RS symbol carried over transmission beam D. In this way,the UE may identify the reception beams X, Y, Z, and W for each of thetransmission beams A, B, C, and D in the base station determinedsequence.

As a result, at 1230, the UE may determine the sequence of transmissionbeams which the base station determined at 1216. For example, asillustrated and described above with respect to FIG. 9, in response toidentifying reception beam X for the first and second CSI-RS symbols,the UE may determine that the transmission beam sequence begins with A.Next, in response to identifying reception beam Y for the third andfourth CSI-RS symbols, the UE may determine that the transmission beamsequence continues with B. Subsequently, in response to identifyingreception beam Z for the fifth CSI-RS symbol, the UE may determine thatthe transmission beam sequence continues with C. Finally, in response toidentifying reception beam W for the sixth CSI-RS symbol, the UE maydetermine that the transmission beam sequence ends with D. Therefore,the UE may determine the transmission beam sequence to be A-B-C-D (inthe example of FIG. 9) in response to identifying the reception beamsfor each transmission beam at 1222.

The UE may similarly identify reception beams for each transmission beamat 1222 and determine the sequence of transmission beams at 1230 basedon the configuration 1214 of transmission beam groups. For example, asillustrated and described above with respect to FIG. 10, the UE maysimultaneously measure SNRs over reception beams X and W during thefirst CSI-RS symbol and simultaneously measure SNRs over reception beamsY and Z during the second CSI-RS symbol, and determine that receptionbeam W is associated with the highest SNR. Thus, the UE may identifyreception beam W for the initial transmission beams carrying the CSI-RS,determine that the first and second CSI-RS symbols were accordinglycarried over transmission beam D, and infer from the determinedtransmission beam D that the base station has initially selected Group1={A, D}. In response to determining that Group 1 was selected by thebase station, the UE may perform multiple SNR measurements during thethird CSI-RS symbol and identify reception beam X for the nexttransmission beam A, since A and D are in the same transmission beamgroup. The UE may then perform multiple SNR measurements during thefourth CSI-RS symbol and identify reception beam Z for the nexttransmission beam C, and similarly reception beam Y for the lasttransmission beam B, while eliminating reception beams X and W duringthese SNR measurements based on the determination that Group 2={B, C} isnow selected. As a result, the UE may determine the sequence oftransmission beams to be D-A-C-B in the example of FIG. 10.

In another example, if any indistinguishable reception beams are presentin the distinguishable beam pairs 1212, the base station may separateassociated transmission beams into different groups in the configuration1214. Based on the configuration 1214 of transmission beam groups, theUE may similarly identify reception beams for each transmission beam at1222 and determine the sequence of transmission beams at 1230. Forinstance, as illustrated and described above with respect to FIG. 11,the UE may identify reception beam X for the first two CSI-RS symbolscarried over transmission beam A, reception beam W for the next twoCSI-RS symbols carried over transmission beam D, and reception beams Zand X for the final two CSI-RS symbols carried over transmission beams Cand B respectively. Moreover, the UE may determine the sequence oftransmission beams to be A-D-C-B in this example of FIG. 11.

In an alternative example referring to SRS rather than CSI-RS, the rolesof the UE and base station described above may be reversed. Forinstance, at 1232, the UE may determine a sequence of transmissionbeams. For example, the UE may determine the sequence of transmissionbeams from the transmission beams indicated in the distinguished beampairs 1212. For instance, the UE may arbitrarily determine atransmission beam sequence from one of multiple permutations orcombinations of transmission beam candidates identified in thedistinguished beam pairs of FIG. 5 (e.g., transmission beams A, B, C,D), such as one of the sequences illustrated and described above withrespect to FIGS. 7A-7B and 9-11 (e.g., C-B-D-A, A-D-C-B, A-B-C-D,D-A-C-B, etc.). Moreover, when transmission beam groups are configured(e.g., in configuration 1214), the UE may also determine a group orderand a beam order within each group when determining the sequence oftransmission beams. For example, similar to that described above withrespect to FIGS. 10 and 11, the UE may determine the transmission beamsequence as a result of randomly selecting Group 1 or Group 2, the beamorder in the randomly selected group, and then the beam order in theremaining group.

Afterwards, at 1234, the UE associates a SRS 1236 with each transmissionbeam in the determined sequence at 1232. For example, similar to thatillustrated and described above with respect to FIGS. 7A-7B and 9-11,the UE may configure SRS symbols for transmission over the varioustransmission beams in the determined transmission beam sequence (similarto CSI-RS symbols 702, 752, 902, 1002, 1102). The number of SRS symbolsM may depend on the number of transmission beam candidates in thedistinguished beam pairs 1212, the configuration 1214 of transmissionbeam groups if present, and the presence if any of indistinguishablereception beams in the distinguished beam pairs. The UE may then sendthe SRS 1236 to the base station over the transmission beams in thedetermined sequence. For example, the UE may send the SRS to the basestation for the base station to measure during beam management.

At 1238, the base station may identify a reception beam for eachtransmission beam carrying the SRS 1236. For example, similar to thatillustrated and described above with respect to FIGS. 9-11, the basestation may identify a best reception beam (e.g., a reception beamassociated with the highest SNR) for receiving each SRS over thetransmission beams. In one example, at 1240, the base station mayperform a plurality of channel measurements of SRS during a symbol overdifferent reception beams. For instance, similar to that illustrated anddescribed above with respect to FIG. 9, the base station maysimultaneously measure the SNRs over reception beams X and Y during thefirst SRS symbol carried over transmission beam A, as well as the SNRsover reception beam Z and W during the second SRS symbol also carriedover transmission beam A. In such case, the base station may determinethat reception beam X is associated with the highest SNR. Thus, the basestation may identify reception beam X for the initial transmission beamscarrying the SRS. Then, at 1242, the base station may identify adistinguishable beam pair for the SRS. For instance, similar to thatillustrated and described above with respect to FIGS. 5 and 9, the basestation may check the set of distinguishable beam pairs (e.g.,distinguishable beam pairs 1212) and determine that reception beam X ispaired with transmission beam A. As a result, the base station maydetermine that the first and second SRS symbols were transmitted overtransmission beam A, and thus that the transmission beam sequencedetermined at 1232 begins with transmission beam A. Furthermore, at1244, the base station may refrain from performing subsequent channelmeasurements with the distinguishable beam pair. For instance, similarto that illustrated and described above with respect to FIG. 9, the basestation may determine that transmission beam A will not be used for theremaining SRS symbols since the UE does not transmit sequences withduplicate or missing transmission beams, and so the base station mayeliminate reception beam X from its subsequent measurements. As aresult, when the UE transmits the next two SRS symbols over transmissionbeam B, the base station may only measure SNRs over reception beams Y,Z, and W (and not X). The base station may then repeat theaforementioned process over the remaining SRS symbols, similar to thatillustrated and described above with respect to FIG. 9, to identify theother reception beams, including reception beam Y for the third andfourth SRS symbols carried over transmission beam B, reception beam Zfor the fifth SRS symbol carried over transmission beam C, and receptionbeam W for the sixth SRS symbol carried over transmission beam D. Inthis way, the base station may identify the reception beams X, Y, Z, andW for each of the transmission beams A, B, C, and D in the UE determinedsequence.

As a result, at 1246, the base station may determine the sequence oftransmission beams which the UE determined at 1232. For example, similarto that illustrated and described above with respect to FIG. 9, inresponse to identifying reception beam X for the first and second SRSsymbols, the base station may determine that the transmission beamsequence begins with A. Similarly, in response to identifying receptionbeam Y for the third and fourth SRS symbols, the base station maydetermine that the transmission beam sequence continues with B.Similarly, in response to identifying reception beam Z for the fifth SRSsymbol, the base station may determine that the transmission beamsequence continues with C. Similarly, in response to identifyingreception beam W for the sixth SRS symbol, the base station maydetermine that the transmission beam sequence ends with D. Therefore,the base station may determine the transmission beam sequence to beA-B-C-D in response to identifying the reception beams for eachtransmission beam at 1238.

The base station may similarly identify reception beams for eachtransmission beam at 1238 and determine the sequence of transmissionbeams at 1246 based on the configuration 1214 of transmission beamgroups. For example, similar to that illustrated and described abovewith respect to FIG. 10, the base station may simultaneously measureSNRs over reception beams X and W during the first SRS symbol and overreception beams Y and Z during the second SRS symbol, and determine thatreception beam W is associated with the highest SNR. Thus, the basestation may identify reception beam W for the initial transmission beamscarrying the SRS, determine that the first and second SRS symbols wereaccordingly carried over transmission beam D, and infer from thedetermined transmission beam D that the UE has initially selected Group1={A, D}. In response to determining that Group 1 was selected by theUE, the base station may perform multiple SNR measurements during thethird SRS symbol and identify reception beam X for the next transmissionbeam A, since A and D are in the same transmission beam group. The basestation may then perform multiple SNR measurements during the fourth SRSsymbol and identify reception beam Z for the next transmission beam C,and similarly reception beam Y for the last transmission beam B, whileeliminating reception beams X and W during these SNR measurements basedon the determination that Group 2={B, C} is now selected. As a result,the base station may determine the sequence of transmission beams to beD-A-C-B in the example of FIG. 10.

Alternatively, if any indistinguishable reception beams are present inthe distinguishable beam pairs 1212, the UE may separate associatedtransmission beams into different groups in the configuration 1214.Based on the configuration 1214 of transmission beam groups, the basestation may similarly identify reception beams for each transmissionbeam at 1238 and determine the sequence of transmission beams at 1246.For instance, similar to that illustrated and described above withrespect to FIG. 11, the base station may identify reception beam X forthe first two SRS symbols carried over transmission beam A, receptionbeam W for the next two SRS symbols carried over transmission beam D,and reception beams Z and X for the final two SRS symbols carried overtransmission beams C and B respectively. Moreover, the base station maydetermine the sequence of transmission beams to be A-D-C-B in thisexample of FIG. 11.

Thus, while 1216, 1218, 1220, 1222, 1224, 1226, 1228, and 1230 refer toa base station (or other wireless device 1204) determining a sequence oftransmission beams, the base station sending CSI-RS symbols over eachtransmission beam to the UE, the UE performing multiple RF measurementsduring each CSI-RS symbol to identify the best reception beams, and theUE (or other wireless device 1202) subsequently determining thetransmission beam sequence which the base station impliedly conveys, theroles of the base station and UE may be reversed, as described abovewith respect to 1232, 1234, 1236, 1238, 1240, 1242, 1244, and 1246. Therole of the base station and UE in either example may depend on theidentity of the receiving device in beam management (the device managingreception beams). For example, if beam management is performed withCSI-RS and the receiving device is wireless device 1202 (e.g., a UE),then the process may be performed as described above with respect to1216, 1218, 1220, 1222, 1224, 1226, 1228, and 1230. Alternatively, ifbeam management is performed with SRS and the receiving device iswireless device 1204 (e.g., a base station), then the process may beperformed as similarly described above with respect to 1232, 1234, 1236,1238, 1240, 1242, 1244, and 1246.

FIG. 13 is a flowchart 1300 of a method of wireless communication. Themethod may be performed by a first wireless device (e.g., wirelessdevice 1202 or 1204, the apparatus 1502, 1602). For example, the firstwireless device may be UE (e.g., the UE 104, 350, 408), a relay orsidelink node, a CPE, a repeater, or an IAB node. Alternatively, thefirst wireless device may be a base station (e.g., the base station102/180, 310, 406), a TRP, a repeater, or an IAB node. Optional aspectsare illustrated in dashed lines. The method allows the first wirelessdevice (a receiving device) in beam management to determine a sequenceof transmission beams impliedly conveyed by a second wireless device (atransmitting device) in a beam sequence conveyance mode.

At 1302, the first wireless device may report to the second wirelessdevice a capability for performing a plurality of channel measurementsduring a symbol length and for performing a number of reception beamswitches over a defined time period. For example, 1302 may be performedby capability report component 1540, 1640. For instance, as describedabove with respect to FIG. 12, wireless device 1202 may provide acapability report 1206 to wireless device 1204 indicating a capabilityof wireless device 1202 to perform multiple RF measurements during asymbol length (e.g., two, four, or other number of measurements) and forperforming a number of reception beam switches over a defined timeperiod (e.g., ten measurements over six symbols). The report may alsoindicate a maximum number of reception beam switches that areperformable during a time period over one of the transmission beams. Forinstance, capability report 1206 may indicate that wireless device 1202may perform up to two, four, or other maximum number of measurementsduring a time period (e.g., two symbols) of reference signals carriedover the same transmission beam.

At 1304, the first wireless device may receive, prior to obtaining aplurality of reference signals, a message from the second wirelessdevice indicating a beam sequence conveyance mode. For example, 1304 maybe performed by message component 1542, 1642. For instance, as describedabove with respect to FIG. 12, wireless device 1202 may receive amessage 1208 from wireless device 1204 indicating a beam sequenceconveyance mode prior to receiving CSI-RS 1220. The beam sequenceconveyance mode may indicate to wireless device 1202 whether wirelessdevice 1204 will impliedly convey an arbitrarily determined sequence oftransmission beams during beam management, such as described above withrespect to FIGS. 9-11, or whether the wireless device 1204 will merelytransmit CSI-RS symbols according to a fixed transmission beam sequenceduring beam management (e.g., a pre-configured sequence previouslyagreed between the base station and UE or some other fixed sequence),such as described above with respect to FIG. 6.

At 1306, the first wireless device may provide an indication of aplurality of distinguishable beam pairs to the second wireless device.For example, 1306 may be performed by distinguishable beam paircomponent 1544, 1646. The distinguishable beam pairs may also be updatedin response to changes in channel conditions. For instance, as describedabove with respect to FIG. 12, wireless device 1202 may provide a set ofdistinguishable beam pairs 1212 to wireless device 1204. For example, asdescribed above with respect to FIG. 5, the UE may report to the basestation an indication that beam pairs AX, BY, CZ, and DW aredistinguishable beam pairs. Additionally, wireless device 1202 mayconstantly update and report the set of distinguishable beam pairs 1212to wireless device 1204 in response to changes in channel conditions(e.g., in response to user mobility, change in channel environment,blockage conditions, etc.).

At 1308, the first wireless device may obtain a configuration oftransmission beam groups from the second wireless device, wheredifferent transmission beams constitute each of the transmission beamgroups. For example, 1308 may be performed by transmission beam groupcomponent 1546, 1648. For instance, as described above with respect toFIG. 12, wireless device 1202 may obtain configuration 1214 oftransmission beam groups from wireless device 1204. The transmissionbeam groups may include different transmission beams, such as describedabove with respect to FIGS. 10 and 11. The transmission beam groups mayalso be specific to the first wireless device. For example, wirelessdevice 1204 (e.g., a base station) may configure a specific number ofgroups with specific transmission beams for wireless device 1202 (e.g.,one UE), such as Group 1: {A, D} and Group 2: {B, C}, while configuringa different number of groups with different transmission beams foranother wireless device (e.g., another UE).

Furthermore, two or more transmission beams of beam pairs having acommon one of the reception beams may be separated into differenttransmission beam groups. For example, as described above with respectto FIG. 11, if during beam training, wireless device 1202 identifies andreports the best K beam pairs as AX, BX, CZ, and DW, then transmissionbeams A and B are both associated with common reception beam X, which istherefore not a distinguishable reception beam. As a result, wirelessdevice 1204 may select the groups such that Group 1={A, D} and Group2={B, C} to ensure that transmission beams A and B are in differenttransmission beam groups and thus are pairwise distinguishable withineach group.

At 1310, the first wireless device obtains the plurality of referencesignals from a second wireless device, where each of the referencesignals is associated with a different transmission beam. For example,1310 may be performed by reference signal component 1548, 1652. Forinstance, as described above with respect to FIG. 12, wireless device1202 may obtain CSI-RS 1220 from wireless device 1204 over varioustransmission beams that wireless device 1204 may associate with thereference signals at 1218. For example, as illustrated and describedabove with respect to FIGS. 7A-7B and 9-11, the base station mayconfigure CSI-RS symbols 702, 752, 902, 1002, 1102 for transmission tothe UE over different transmission beams (e.g., transmission beams 402in FIG. 4, such as A, B, C, D) according to the transmission beamsequence determined at 1216. Similarly, wireless device 1204 may obtainSRS 1236 from wireless device 1202 over various transmission beams thatwireless device 1202 may associate with the reference signals at 1234.

At 1312, the first wireless device identifies a reception beam for eachof the transmission beams, where the identified reception beams comprisedifferent reception beams or at least one common reception beam. Forexample, 1312 may be performed by reception beam component 1550. Forinstance, as described above with respect to FIG. 12, at 1222, wirelessdevice 1202 may identify a reception beam for each of the transmissionbeams carrying CSI-RS 1220. For example, as illustrated and describedabove with respect to FIGS. 9-11, the UE may identify a best receptionbeam (e.g., a reception beam associated with the highest SNR) forreceiving each CSI-RS symbol 702, 752, 902, 1002, 1102 over the varioustransmission beams that wireless device 1204 associates with thereference signals. The UE may identify different reception beams such asillustrated in FIGS. 9 and 10 (e.g., X, Y, Z, W), or at least one commonreception beam such as illustrated in FIG. 11 (e.g., X, X, Z, W).Similarly, at 1238, wireless device 1204 may identify a reception beamfor each of the transmission beams carrying SRS 1236.

The first wireless device may identify reception beams at 1312 inresponse to steps 1314, 1316, and 1318. For instance, at 1314, the firstwireless device may perform a plurality of channel measurements of oneof the reference signals during a symbol, where each of the channelmeasurements is associated with a different one of the reception beams.For example, 1314 may be performed by reception beam component 1550. Forinstance, as described above with respect to FIG. 12, at 1224, wirelessdevice 1202 may perform a plurality of channel measurements of CSI-RS1220 during a symbol (e.g., CSI-RS symbol 702, 752, 902, 1002, 1102)over different reception beams. For instance, as illustrated anddescribed above with respect to FIG. 9, the UE may simultaneouslymeasure the SNRs over reception beams X and Y during the first CSI-RSsymbol carried over transmission beam A, as well as the SNRs overreception beam Z and W during the second CSI-RS symbol also carried overtransmission beam A. In such case, the UE may determine that receptionbeam X is associated with the highest SNR. Thus, the UE may identifyreception beam X for the initial transmission beams carrying the CSI-RS.Similarly, at 1240, wireless device 1204 may perform a plurality ofchannel measurements of SRS 1236 during a symbol over differentreception beams.

Next, at 1316, the first wireless device identifies a distinguishablebeam pair for the one of the reference signals in response to thechannel measurements. For example, 1316 may be performed by receptionbeam component 1550. One of the distinguishable beam pairs may includeone of the transmission beams and one of the reception beams, and adifference between a first signal strength of the reference signalassociated with the one of the transmission beams received over the oneof the reception beams and a second signal strength of the referencesignal associated with the one of the transmission beams received overanother of the reception beams may exceed a signal strength threshold.The signal strength threshold may be obtained in a configuration fromthe second wireless device. For instance, as described above withrespect to FIG. 12, at 1226, wireless device 1202 may identify adistinguishable beam pair for the CSI-RS 1220 in response to themeasurements performed at 1224. The distinguishable beam pair may be oneof the distinguishable beam pairs 1212 reported to wireless device 1204.For example, as illustrated and described above with respect to FIGS. 5and 9, in response to determining that reception beam X is associatedwith the highest SNR, the UE may check the set of distinguishable beampairs 502 and identify that AX is a distinguishable beam pair in theset, where the difference between the SNR of AX and the maximum SNR of(AY, AZ, AW) exceeds the signal strength threshold (e.g.,SNR_(threshold)) obtained from the base station. SNR_(threshold) maycorrespond to the signal strength threshold 1210 that wireless device1202 obtains from wireless device 1204 in FIG. 12. The UE may alsodetermine that reception beam X is paired with transmission beam A inthe distinguishable beam pairs. As a result, the UE may determine thatthe first and second CSI-RS symbols were transmitted over transmissionbeam A, and thus that the transmission beam sequence determined at 1216begins with transmission beam A. Similarly, at 1242, wireless device1204 may identify a distinguishable beam pair for the SRS 1236 inresponse to the measurements performed at 1240, and likewise identifythat the transmission beam sequence determined at 1232 begins withtransmission beam A.

Then, at 1318, the first wireless device refrains from performingsubsequent channel measurements with the distinguishable beam pair. Forexample, 1318 may be performed by reception beam component 1550. Forexample, as described above with respect to FIG. 12, at 1228, wirelessdevice 1202 may refrain from performing subsequent channel measurementswith the distinguishable beam pair identified at 1226. For instance, asillustrated and described above with respect to FIG. 9, afterdetermining that reception beam X is paired with transmission beam A inthe distinguishable beam pairs and thus that the first and second CSI-RSsymbols were transmitted over transmission beam A, the UE may determinethat transmission beam A will not be used for the remaining CSI-RSsymbols since the base station does not transmit sequences withduplicate or missing transmission beams. Therefore, the UE may eliminatereception beam X from its subsequent measurements. As a result, when thebase station transmits the next two CSI-RS symbols over transmissionbeam B, the UE may only measure SNRs over reception beams Y, Z, and W(and not X). Similarly, at 1244, wireless device 1204 may refrain fromperforming subsequent channel measurements with the distinguishable beampair identified at 1242, and after determining that reception beam X ispaired with transmission beam A in the distinguishable beam pairs,likewise only measure SNRs over reception beams Y, Z, and W (and not X).

The first wireless device may then repeat the aforementioned processdescribed at 1312, 1314, 1316, and 1318 over the remaining referencesignal symbols to identify the other reception beams. For instance,referring to FIG. 12, after wireless device 1202 identifies at 1222 areception beam X for the first and second CSI-RS symbols carried overtransmission beam A, the wireless device may apply similar processes at1222, 1224, 1226 and 1228 to identify the other reception beams. Forexample, as illustrated and described above with respect to FIG. 9, theUE may identify reception beam Y for the third and fourth CSI-RS symbolscarried over transmission beam B, reception beam Z for the fifth CSI-RSsymbol carried over transmission beam C, and reception beam W for thesixth CSI-RS symbol carried over transmission beam D. In this way, theUE may identify the reception beams X, Y, Z, and W for each of thetransmission beams A, B, C, and D in the base station determinedsequence. Similarly, after wireless device 1204 identifies at 1238 areception beam X for the first and second SRS symbols carried overtransmission beam A, the wireless device may apply similar processes at1238, 1240, 1242, and 1244 to identify the other reception beams.

Finally, at 1320, the first wireless device determines a sequence of thetransmission beams in response to the identification. For example, 1320may be performed by sequence determination component 1552. The sequencemay be determined in response to the message. For instance, as describedabove with respect to FIG. 12, at 1230, wireless device 1202 maydetermine the sequence of transmission beams selected by wireless device1204 at 1216 in response to identifying the reception beams at 1222. Forexample, as illustrated and described above with respect to FIG. 9, inresponse to identifying reception beam X for the first and second CSI-RSsymbols, the UE may determine that the transmission beam sequence beginswith A. Next, in response to identifying reception beam Y for the thirdand fourth CSI-RS symbols, the UE may determine that the transmissionbeam sequence continues with B. Subsequently, in response to identifyingreception beam Z for the fifth CSI-RS symbol, the UE may determine thatthe transmission beam sequence continues with C. Finally, in response toidentifying reception beam W for the sixth CSI-RS symbol, the UE maydetermine that the transmission beam sequence ends with D. Therefore,the UE may determine the transmission beam sequence to be A-B-C-D (inthe example of FIG. 9) in response to identifying the reception beamsfor each transmission beam at 1222. Similarly, at 1246, wireless device1204 may determine the sequence of transmission beams selected bywireless device 1202 at 1232 in response to identifying the receptionbeams at 1238. Wireless device 1202 may perform the processes at 1222,1224, 1226, 1228, and 1230 in response to receiving message 1208 fromwireless device 1204 indicating the beam sequence conveyance mode.Similarly, wireless device 1204 may perform the processes at 1238, 1240,1242, 1244, and 1246 in response to the beam sequence conveyance mode.

FIG. 14 is a flowchart 1400 of a method of wireless communication. Themethod may be performed by a first wireless device (e.g., wirelessdevice 1204, the apparatus 1602). For example, the first wireless devicemay be a base station (e.g., the base station 102/180, 310, 406), a TRP,a repeater, or an IAB node. Optional aspects are illustrated in dashedlines. The method allows the first wireless device (a transmittingdevice) in beam management to impliedly convey a sequence oftransmission beams to a second wireless device (a receiving device) in abeam sequence conveyance mode.

At 1402, the first wireless device may receive a capability report fromthe second wireless device indicating a capability for performing aplurality of channel measurements during a symbol length and forperforming a number of reception beam switches over a defined timeperiod. For example, 1402 may be performed by capability reportcomponent 1640. The report may indicate a maximum number of repetitionbeam switches that are performable by the second wireless device duringa time period over one of the transmission beams. For instance, asdescribed above with respect to FIG. 12, wireless device 1202 mayprovide a capability report 1206 to wireless device 1204 indicating acapability of wireless device 1202 to perform multiple RF measurementsduring a symbol length (e.g., two, four, or other number ofmeasurements) and for performing a number of reception beam switchesover a defined time period (e.g., ten measurements over six symbols).The report may also indicate a maximum number of reception beam switchesthat are performable during a time period over one of the transmissionbeams. For instance, capability report 1206 may indicate that wirelessdevice 1202 may perform up to two, four, or other maximum number ofmeasurements during a time period (e.g., two symbols) of referencesignals carried over the same transmission beam.

At 1404, the first wireless device provides a message to the secondwireless device indicating a beam sequence conveyance mode. For example,1404 may be performed by message component 1642. The message may beprovided in response to the capability report received at 1402. Forinstance, as described above with respect to FIG. 12, wireless device1202 may receive a message 1208 from wireless device 1204 indicating abeam sequence conveyance mode prior to receiving CSI-RS 1220. The beamsequence conveyance mode may indicate to wireless device 1202 whetherwireless device 1204 will impliedly convey an arbitrarily determinedsequence of transmission beams during beam management, such as describedabove with respect to FIGS. 9-11, or whether the wireless device 1204will merely transmit CSI-RS symbols according to a fixed transmissionbeam sequence during beam management (e.g., a pre-configured sequencepreviously agreed between the base station and UE or some other fixedsequence), such as described above with respect to FIG. 6.

At 1406, the first wireless device may provide a signal strengththreshold to the second wireless device. For example, 1406 may beperformed by signal strength threshold component 1644. For instance,wireless device 1204 may provide signal strength threshold 1210 (e.g.,SNR_(threshold) for distinguishable beam pairs) to wireless device 1202.

At 1408, the first wireless device may receive an indication of aplurality of distinguishable beam pairs from the second wireless devicein response to the message provided at 1404. For example, 1408 may beperformed by distinguishable beam pair component 1646. For instance, asdescribed above with respect to FIG. 12, wireless device 1202 mayprovide a set of distinguishable beam pairs 1212 to wireless device 1204in response to receiving message 1208. For example, as described abovewith respect to FIG. 5, the UE may report to the base station anindication that beam pairs AX, BY, CZ, and DW are distinguishable beampairs.

One of the distinguishable beam pairs may include one of thetransmission beams and one of a plurality of reception beams, where adifference between a first signal strength of the reference signalassociated with the one of the transmission beams over the one of thereception beams and a second signal strength of the reference signalassociated with the one of the transmission beams over another of thereception beams exceeds a signal strength threshold. For example, asdescribed above with respect to FIG. 5, if beam pairs AX, AY, AZ, and AWare respectively associated with SNRs 25 dB, 12 dB, 4 dB, and −2 dBrespectively, where SNR_(threshold)=7 dB, then best beam pair AX is adistinguishable beam pair since the difference between its SNR (i.e. 25dB) and the maximum SNR out of the SNRs associated with the other beampairs AY, AZ, and AW (i.e., 12 dB, leading to a difference of 25−12=13dB) exceeds SNR_(threshold) (i.e., 13 dB>7 dB).

At 1410, the first wireless device may provide a configuration oftransmission beam groups to the second wireless device, where differenttransmission beams constitute each of the transmission beam groups. Forexample, 1410 may be performed by transmission beam group component1648. For instance, as described above with respect to FIG. 12, wirelessdevice 1202 may obtain configuration 1214 of transmission beam groupsfrom wireless device 1204. The transmission beam groups may includedifferent transmission beams, such as described above with respect toFIGS. 10 and 11. The transmission beam groups may also be specific tothe second wireless device. For example, wireless device 1204 (e.g., abase station) may configure a specific number of groups with specifictransmission beams for wireless device 1202 (e.g., one UE), such asGroup 1: {A, D} and Group 2: {B, C}, while configuring a differentnumber of groups with different transmission beams for another wirelessdevice (e.g., another UE).

Moreover, two or more transmission beams of beam pairs having a commonreception beam may be separated into different transmission beam groups.For example, as described above with respect to FIG. 11, if during beamtraining, wireless device 1202 identifies and reports the best K beampairs as AX, BX, CZ, and DW, then transmission beams A and B are bothassociated with common reception beam X, which is therefore not adistinguishable reception beam. As a result, wireless device 1204 mayselect the groups such that Group 1={A, D} and Group 2={B, C} to ensurethat transmission beams A and B are in different transmission beamgroups and thus are pairwise distinguishable within each group.

At 1412, the first wireless device may determine a sequence of differenttransmission beams. For example, 1412 may be performed by sequencecomponent 1650. For instance, as described above with respect to FIG.12, at 1216, wireless device 1204 may determine a sequence oftransmission beams (e.g., transmission beams 402 in FIG. 4). Forinstance, the base station may arbitrarily determine a transmission beamsequence from one of multiple permutations or combinations oftransmission beam candidates identified in the distinguished beam pairsof FIG. 5 (e.g., transmission beams A, B, C, D), such as one of thesequences illustrated and described above with respect to FIGS. 7A-7Band 9-11 (e.g., C-B-D-A, A-D-C-B, A-B-C-D, D-A-C-B, etc.). Moreover,when transmission beam groups are configured (e.g., in configuration1214), the base station may also determine a group order and a beamorder within each group when determining the sequence of transmissionbeams. For example, as described above with respect to FIGS. 10 and 11,the base station may determine the transmission beam sequence as aresult of randomly selecting Group 1 or Group 2, the beam order in therandomly selected group, and then the beam order in the remaining group.

Finally, at 1414, the first wireless device may associate a referencesignal with each one of the transmission beams for transmission to thesecond wireless device according to the sequence. For example, 1414 maybe performed by reference signal component 1652. For instance, asdescribed above with respect to FIG. 12, at 1218, wireless device 1204may associate a CSI-RS with each transmission beam in the transmissionbeam sequence determined at 1216. For example, as illustrated anddescribed above with respect to FIGS. 7A-7B and 9-11, the base stationmay configure CSI-RS symbols 702, 752, 902, 1002, 1102 for transmissionover the various transmission beams in the determined transmission beamsequence. The number of CSI-RS symbols M may depend on the number oftransmission beam candidates in the distinguished beam pairs 1212, theconfiguration 1214 of transmission beam groups if present, and thepresence if any of indistinguishable reception beams in thedistinguished beam pairs. The base station may then send the CSI-RS 1220to the UEs over the transmission beams in the determined sequence. Forexample, the base station may send the CSI-RS to the UE for the UE tomeasure during beam management.

FIG. 15 is a diagram 1500 illustrating an example of a hardwareimplementation for an apparatus 1502. The apparatus 1502 is a UE andincludes a cellular baseband processor 1504 (also referred to as amodem) coupled to a cellular RF transceiver 1522 and one or moresubscriber identity modules (SIM) cards 1520, an application processor1506 coupled to a secure digital (SD) card 1508 and a screen 1510, aBluetooth module 1512, a wireless local area network (WLAN) module 1514,a Global Positioning System (GPS) module 1516, and a power supply 1518.The cellular baseband processor 1504 communicates through the cellularRF transceiver 1522 with the UE 104 and/or BS 102/180. The cellularbaseband processor 1504 may include a computer-readable medium/memory.The computer-readable medium/memory may be non-transitory. The cellularbaseband processor 1504 is responsible for general processing, includingthe execution of software stored on the computer-readable medium/memory.The software, when executed by the cellular baseband processor 1504,causes the cellular baseband processor 1504 to perform the variousfunctions described supra. The computer-readable medium/memory may alsobe used for storing data that is manipulated by the cellular basebandprocessor 1504 when executing software. The cellular baseband processor1504 further includes a reception component 1530, a communicationmanager 1532, and a transmission component 1534. The communicationmanager 1532 includes the one or more illustrated components. Thecomponents within the communication manager 1532 may be stored in thecomputer-readable medium/memory and/or configured as hardware within thecellular baseband processor 1504. The cellular baseband processor 1504may be a component of the UE 350 and may include the memory 360 and/orat least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359. In one configuration, the apparatus 1502 maybe a modem chip and include just the baseband processor 1504, and inanother configuration, the apparatus 1502 may be the entire UE (e.g.,see 350 of FIG. 3) and include the aforediscussed additional modules ofthe apparatus 1502.

The communication manager 1532 includes a capability report component1540 that is configured to report to the second wireless device acapability for performing a plurality of channel measurements during asymbol length and for performing a number of reception beam switchesover a defined time period, e.g., as described in connection with 1302.The communication manager 1532 further includes a message component 1542that receives input in the form of the capability from the capabilityreport component 1540 and is configured to receive, prior to obtaining aplurality of reference signals, a message from the second wirelessdevice indicating a beam sequence conveyance mode, e.g., as described inconnection with 1304. The communication manager 1532 further includes adistinguishable beam pair component 1544 that receives input in the formof the message from the message component 1542 and is configured toprovide an indication of a plurality of distinguishable beam pairs tothe second wireless device, e.g., as described in connection with 1306.The communication manager 1532 further includes a transmission beamgroup component 1546 that receives input in the form of the message fromthe message component 1542 and is configured to obtain a configurationof transmission beam groups from the second wireless device, wheredifferent transmission beams constitute each of the transmission beamgroups, e.g., as described in connection with 1308. The communicationmanager 1532 further includes a reference signal component 1548 thatreceives input in the form of the message from the message component1542 and is configured to obtain a plurality of reference signals from asecond wireless device, wherein each of the reference signals isassociated with a different transmission beam, e.g., as described inconnection with 1310. The communication manager 1532 further includes areception beam component 1550 that receives input in the form of themessage from the message component 1542 and is configured to identify areception beam for each of the transmission beams, where the identifiedreception beams comprise different reception beams or at least onecommon reception beam, e.g., as described in connection with 1312, 1314,1316, and 1318. The communication manager 1532 further includes asequence determination component 1552 that receives input in the form ofthe message from the message component 1542 and is configured todetermine a sequence of the transmission beams in response to theidentification, e.g., as described in connection with 1320.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIGS. 12 and13. As such, each block in the aforementioned flowcharts of FIGS. 12 and13 may be performed by a component and the apparatus may include one ormore of those components. The components may be one or more hardwarecomponents specifically configured to carry out the statedprocesses/algorithm, implemented by a processor configured to performthe stated processes/algorithm, stored within a computer-readable mediumfor implementation by a processor, or some combination thereof.

In one configuration, the apparatus 1502, and in particular the cellularbaseband processor 1504, includes means for obtaining a plurality ofreference signals from a second wireless device, wherein each of thereference signals is associated with a different transmission beam;means for identifying a reception beam for each of the transmissionbeams, where the identified reception beams comprise different receptionbeams or at least one common reception beam; and means for determining asequence of the transmission beams in response to the identification.

In one configuration, the apparatus 1502, and in particular the cellularbaseband processor 1504, may include means for performing a plurality ofchannel measurements of one of the reference signals during a symbol,wherein each of the channel measurements is associated with a differentone of the reception beams.

In one configuration, the apparatus 1502, and in particular the cellularbaseband processor 1504, may include means for identifying adistinguishable beam pair for the one of the reference signals inresponse to the channel measurements; and means for refraining fromperforming subsequent channel measurements with the distinguishable beampair.

In one configuration, the apparatus 1502, and in particular the cellularbaseband processor 1504, may include means for providing an indicationof a plurality of distinguishable beam pairs to the second wirelessdevice.

In one configuration, the apparatus 1502, and in particular the cellularbaseband processor 1504, may include means for reporting to the secondwireless device a capability for performing a plurality of channelmeasurements during a symbol length and for performing a number ofreception beam switches over a defined time period.

In one configuration, the apparatus 1502, and in particular the cellularbaseband processor 1504, may include means for obtaining a configurationof transmission beam groups from the second wireless device, whereindifferent transmission beams constitute each of the transmission beamgroups.

In one configuration, the apparatus 1502, and in particular the cellularbaseband processor 1504, may include means for receiving, prior toobtaining the plurality of reference signals, a message from the secondwireless device indicating a beam sequence conveyance mode, wherein thesequence is further determined in response to the message.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 1502 configured to perform the functionsrecited by the aforementioned means. As described supra, the apparatus1502 may include the TX Processor 368, the RX Processor 356, and thecontroller/processor 359. As such, in one configuration, theaforementioned means may be the TX Processor 368, the RX Processor 356,and the controller/processor 359 configured to perform the functionsrecited by the aforementioned means.

FIG. 16 is a diagram 1600 illustrating an example of a hardwareimplementation for an apparatus 1602. The apparatus 1602 is a BS andincludes a baseband unit 1604. The baseband unit 1604 may communicatethrough a cellular RF transceiver with the UE 104. The baseband unit1604 may include a computer-readable medium/memory. The baseband unit1604 is responsible for general processing, including the execution ofsoftware stored on the computer-readable medium/memory. The software,when executed by the baseband unit 1604, causes the baseband unit 1604to perform the various functions described supra. The computer-readablemedium/memory may also be used for storing data that is manipulated bythe baseband unit 1604 when executing software. The baseband unit 1604further includes a reception component 1630, a communication manager1632, and a transmission component 1634. The communication manager 1632includes the one or more illustrated components. The components withinthe communication manager 1632 may be stored in the computer-readablemedium/memory and/or configured as hardware within the baseband unit1604. The baseband unit 1604 may be a component of the BS 310 and mayinclude the memory 376 and/or at least one of the TX processor 316, theRX processor 370, and the controller/processor 375.

The communication manager 1632 includes a capability report component1640 that is configured to receive a capability report from the secondwireless device indicating a capability for performing a plurality ofchannel measurements during a symbol length and for performing a numberof reception beam switches over a defined time period, wherein themessage is provided in response to the report, e.g., as described inconnection with 1402. The communication manager 1632 further includes amessage component 1642 that is configured to provide a message to asecond wireless device indicating a beam sequence conveyance mode, e.g.,as described in connection with 1404. The communication manager 1632further includes a signal strength threshold component 1644 that isconfigured to provide a signal strength threshold to the second wirelessdevice, e.g., as described in connection with 1406. The communicationmanager 1632 further includes a distinguishable beam pair component 1646that is configured to receive an indication of a plurality ofdistinguishable beam pairs from the second wireless device in responseto the message, e.g., as described in connection with 1408. Thecommunication manager 1632 further includes a transmission beam groupcomponent 1648 that is configured to provide a configuration oftransmission beam groups to the second wireless device, whereindifferent transmission beams constitute each of the transmission beamgroups, e.g., as described in connection with 1410. The communicationmanager 1632 further includes a sequence component 1650 that isconfigured to determine a sequence of different transmission beams,e.g., as described in connection with 1412. The communication manager1632 further includes a reference signal component 1652 that isconfigured to associate a reference signal with each one of thetransmission beams for transmission to the second wireless deviceaccording to the sequence, e.g., as described in connection with 1414.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIGS. 12 and14. As such, each block in the aforementioned flowcharts of FIGS. 12 and14 may be performed by a component and the apparatus may include one ormore of those components. The components may be one or more hardwarecomponents specifically configured to carry out the statedprocesses/algorithm, implemented by a processor configured to performthe stated processes/algorithm, stored within a computer-readable mediumfor implementation by a processor, or some combination thereof.

In one configuration, the apparatus 1602, and in particular the basebandunit 1604, includes means for providing a message to a second wirelessdevice indicating a beam sequence conveyance mode; means for determininga sequence of different transmission beams; and means for associating areference signal with each one of the transmission beams fortransmission to the second wireless device according to the sequence.

In one configuration, the apparatus 1602, and in particular the basebandunit 1604, may include means for receiving an indication of a pluralityof distinguishable beam pairs from the second wireless device inresponse to the message.

In one configuration, the apparatus 1602, and in particular the basebandunit 1604, may include means for providing the signal strength thresholdto the second wireless device.

In one configuration, the apparatus 1602, and in particular the basebandunit 1604, may include means for receiving a capability report from thesecond wireless device indicating a capability for performing aplurality of channel measurements during a symbol length and forperforming a number of reception beam switches over a defined timeperiod, wherein the message is provided in response to the report.

In one configuration, the apparatus 1602, and in particular the basebandunit 1604, may include means for providing a configuration oftransmission beam groups to the second wireless device, whereindifferent transmission beams constitute each of the transmission beamgroups.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 1602 configured to perform the functionsrecited by the aforementioned means. As described supra, the apparatus1602 may include the TX Processor 316, the RX Processor 370, and thecontroller/processor 375. As such, in one configuration, theaforementioned means may be the TX Processor 316, the RX Processor 370,and the controller/processor 375 configured to perform the functionsrecited by the aforementioned means.

During beam management, a transmitting device may provide referencesignals over various transmission beams for a receiving device toperform beam signal strength measurements. However, the transmittingdevice generally does not convey information to the receiving deviceregarding the sequence of the various transmission beams. Aspects of thepresent disclosure allow the transmitting device to provide referencesignals to a receiving device for beam management according to anarbitrarily determined sequence of transmission beams at any time, andto implicitly convey information regarding the determined sequence oftransmission beams to the receiving device. Such implicit conveyance oftransmission beam sequences may result in reduced overhead compared toexplicit messages indicating the beam sequence, thereby savingresources. Moreover, the transmitting device may change a transmissionbeam sequence (e.g., to a sequence other than a pre-configured sequencefor beam refinement) at any time, regardless of blockage or interferenceor similar beam failure conditions, since the receiving device may beable to determine the sequence during the measurement process.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of example approaches.Based upon design preferences, it is understood that the specific orderor hierarchy of blocks in the processes/flowcharts may be rearranged.Further, some blocks may be combined or omitted. The accompanying methodclaims present elements of the various blocks in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Terms such as “if,” “when,” and“while” should be interpreted to mean “under the condition that” ratherthan imply an immediate temporal relationship or reaction. That is,these phrases, e.g., “when,” do not imply an immediate action inresponse to or during the occurrence of an action, but simply imply thatif a condition is met then an action will occur, but without requiring aspecific or immediate time constraint for the action to occur. The word“exemplary” is used herein to mean “serving as an example, instance, orillustration.” Any aspect described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otheraspects. Unless specifically stated otherwise, the term “some” refers toone or more. Combinations such as “at least one of A, B, or C,” “one ormore of A, B, or C,” “at least one of A, B, and C,” “one or more of A,B, and C,” and “A, B, C, or any combination thereof” include anycombination of A, B, and/or C, and may include multiples of A, multiplesof B, or multiples of C. Specifically, combinations such as “at leastone of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B,and C,” “one or more of A, B, and C,” and “A, B, C, or any combinationthereof” may be A only, B only, C only, A and B, A and C, B and C, or Aand B and C, where any such combinations may contain one or more memberor members of A, B, or C. All structural and functional equivalents tothe elements of the various aspects described throughout this disclosurethat are known or later come to be known to those of ordinary skill inthe art are expressly incorporated herein by reference and are intendedto be encompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. The words “module,”“mechanism,” “element,” “device,” and the like may not be a substitutefor the word “means.” As such, no claim element is to be construed as ameans plus function unless the element is expressly recited using thephrase “means for.”

The following examples are illustrative only and may be combined withaspects of other embodiments or teachings described herein, withoutlimitation.

Example 1 is a method of wireless communication at a first wirelessdevice, comprising: obtaining a plurality of reference signals from asecond wireless device, wherein each of the reference signals isassociated with a different transmission beam; identifying a receptionbeam for each of the transmission beams, where the identified receptionbeams comprise different reception beams or at least one commonreception beam; and determining a sequence of the transmission beams inresponse to the identification.

Example 2 is the method of Example 1, further comprising: performing aplurality of channel measurements of one of the reference signals duringa symbol, wherein each of the channel measurements is associated with adifferent one of the reception beams.

Example 3 is the method of Example 2, further comprising: identifying adistinguishable beam pair for the one of the reference signals inresponse to the channel measurements; and refraining from performingsubsequent channel measurements with the distinguishable beam pair.

Example 4 is the method of any of Examples 1 to 3, further comprising:providing an indication of a plurality of distinguishable beam pairs tothe second wireless device.

Example 5 is the method of Example 4, wherein one of the distinguishablebeam pairs includes one of the transmission beams and one of thereception beams, and wherein a difference between a first signalstrength of the reference signal associated with the one of thetransmission beams received over the one of the reception beams and asecond signal strength of the reference signal associated with the oneof the transmission beams received over another of the reception beamsexceeds a signal strength threshold.

Example 6 is the method of Example 5, wherein the signal strengththreshold is obtained in a configuration from the second wirelessdevice.

Example 7 is the method of any of Examples 4 to 6, wherein thedistinguishable beam pairs are updated in response to changes in channelconditions.

Example 8 is the method of any of Examples 1 to 7, further comprising:reporting to the second wireless device a capability for performing aplurality of channel measurements during a symbol length and forperforming a number of reception beam switches over a defined timeperiod.

Example 9 is the method of Example 8, wherein the report indicates amaximum number of reception beam switches that are performable during atime period over one of the transmission beams.

Example 10 is the method of any of Examples 1 to 9, further comprising:obtaining a configuration of transmission beam groups from the secondwireless device, wherein different transmission beams constitute each ofthe transmission beam groups.

Example 11 is the method of Example 10, wherein the transmission beamgroups are specific to the first wireless device.

Example 12 is the method of any of Examples 10 and 11, wherein two ormore transmission beams of beam pairs having a common one of thereception beams are separated into different transmission beam groups.

Example 13 is the method of any of Examples 1 to 12, further comprising:receiving, prior to obtaining the plurality of reference signals, amessage from the second wireless device indicating a beam sequenceconveyance mode, wherein the sequence is further determined in responseto the message.

Example 14 is an apparatus for wireless communication, comprising: aprocessor; memory coupled with the processor; and instructions stored inthe memory and operable, when executed by the processor, to cause theapparatus to: obtain a plurality of reference signals from a wirelessdevice, wherein each of the reference signals is associated with adifferent transmission beam; identify a reception beam for each of thetransmission beams, where the identified reception beams comprisedifferent reception beams or at least one common reception beam; anddetermine a sequence of the transmission beams in response to theidentification.

Example 15 is the apparatus of Example 14, wherein the instructions,when executed by the processor, further cause the apparatus to: performa plurality of channel measurements of one of the reference signalsduring a symbol, wherein each of the channel measurements is associatedwith a different one of the reception beams.

Example 16 is the apparatus of Example 15, wherein the instructions,when executed by the processor, further cause the apparatus to: identifya distinguishable beam pair for the one of the reference signals inresponse to the channel measurements; and refrain from performingsubsequent channel measurements with the distinguishable beam pair.

Example 17 is the apparatus of any of Examples 14 to 16, wherein theinstructions, when executed by the processor, further cause theapparatus to: provide an indication of a plurality of distinguishablebeam pairs to the wireless device.

Example 18 is a method of wireless communication at a first wirelessdevice, comprising: providing a message to a second wireless deviceindicating a beam sequence conveyance mode; determining a sequence ofdifferent transmission beams; and associating a reference signal witheach one of the transmission beams for transmission to the secondwireless device according to the sequence.

Example 19 is the method of Example 18, further comprising: receiving anindication of a plurality of distinguishable beam pairs from the secondwireless device in response to the message.

Example 20 is the method of Example 19, wherein one of thedistinguishable beam pairs includes one of the transmission beams andone of a plurality of reception beams, and wherein a difference betweena first signal strength of the reference signal associated with the oneof the transmission beams over the one of the reception beams and asecond signal strength of the reference signal associated with the oneof the transmission beams over another of the reception beams exceeds asignal strength threshold.

Example 21 is the method of Example 20, further comprising: providingthe signal strength threshold to the second wireless device.

Example 22 is the method of any of Examples 18 to 21, furthercomprising: receiving a capability report from the second wirelessdevice indicating a capability for performing a plurality of channelmeasurements during a symbol length and for performing a number ofreception beam switches over a defined time period, wherein the messageis provided in response to the report.

Example 23 is the method of Example 22, wherein the report indicates amaximum number of reception beam switches that are performable by thesecond wireless device during a time period over one of the transmissionbeams.

Example 24 is the method of any of Examples 18 to 23, furthercomprising: providing a configuration of transmission beam groups to thesecond wireless device, wherein different transmission beams constituteeach of the transmission beam groups.

Example 25 is the method of Example 24, wherein the transmission beamgroups are specific to the second wireless device.

Example 26 is the method of any of Examples 24 and 25, wherein two ormore transmission beams of beam pairs having a common reception beam areseparated into different transmission beam groups.

Example 27 is an apparatus for wireless communication, comprising: aprocessor; memory coupled with the processor; and instructions stored inthe memory and operable, when executed by the processor, to cause theapparatus to: provide a message to a wireless device indicating a beamsequence conveyance mode; determine a sequence of different transmissionbeams; and associate a reference signal with each one of thetransmission beams for transmission to the wireless device according tothe sequence.

Example 28 is the apparatus of Example 27, wherein the instructions,when executed by the processor, further cause the apparatus to: providea signal strength threshold to the wireless device.

Example 29 is the apparatus of any of Examples 27 and 28, wherein theinstructions, when executed by the processor, further cause theapparatus to: receive a capability report from the wireless deviceindicating a capability for performing a plurality of channelmeasurements during a symbol length and for performing a number ofreception beam switches over a defined time period, wherein the messageis provided in response to the report.

Example 30 is the apparatus of any of Examples 27 to 29, wherein theinstructions, when executed by the processor, further cause theapparatus to: provide a configuration of transmission beam groups to thewireless device, wherein different transmission beams constitute each ofthe transmission beam groups.

What is claimed is:
 1. A method of wireless communication at a firstwireless device, comprising: obtaining a plurality of reference signalsfrom a second wireless device, wherein each of the reference signals isassociated with a different transmission beam; identifying a receptionbeam for each of the transmission beams, wherein the identifiedreception beams comprise different reception beams or at least onecommon reception beam; and determining a sequence of the transmissionbeams in response to the identification.
 2. The method of claim 1,further comprising: performing a plurality of channel measurements ofone of the reference signals during a symbol, wherein each of thechannel measurements is associated with a different one of the receptionbeams.
 3. The method of claim 2, further comprising: identifying adistinguishable beam pair for the one of the reference signals inresponse to the channel measurements; and refraining from performingsubsequent channel measurements with the distinguishable beam pair. 4.The method of claim 1, further comprising: providing an indication of aplurality of distinguishable beam pairs to the second wireless device.5. The method of claim 4, wherein one of the distinguishable beam pairsincludes one of the transmission beams and one of the reception beams,and wherein a difference between a first signal strength of thereference signal associated with the one of the transmission beamsreceived over the one of the reception beams and a second signalstrength of the reference signal associated with the one of thetransmission beams received over another of the reception beams exceedsa signal strength threshold.
 6. The method of claim 5, wherein thesignal strength threshold is obtained in a configuration from the secondwireless device.
 7. The method of claim 4, wherein the distinguishablebeam pairs are updated in response to changes in channel conditions. 8.The method of claim 1, further comprising: reporting to the secondwireless device a capability for performing a plurality of channelmeasurements during a symbol length and for performing a number ofreception beam switches over a defined time period.
 9. The method ofclaim 8, wherein the report indicates a maximum number of reception beamswitches that are performable during a time period over one of thetransmission beams.
 10. The method of claim 1, further comprising:obtaining a configuration of transmission beam groups from the secondwireless device, wherein different transmission beams constitute each ofthe transmission beam groups.
 11. The method of claim 10, wherein thetransmission beam groups are specific to the first wireless device. 12.The method of claim 10, wherein two or more transmission beams of beampairs having a common one of the reception beams are separated intodifferent transmission beam groups.
 13. The method of claim 1, furthercomprising: receiving, prior to obtaining the plurality of referencesignals, a message from the second wireless device indicating a beamsequence conveyance mode, wherein the sequence is further determined inresponse to the message.
 14. An apparatus for wireless communication,comprising: a processor; memory coupled with the processor; andinstructions stored in the memory and operable, when executed by theprocessor, to cause the apparatus to: obtain a plurality of referencesignals from a wireless device, wherein each of the reference signals isassociated with a different transmission beam; identify a reception beamfor each of the transmission beams, wherein the identified receptionbeams comprise different reception beams or at least one commonreception beam; and determine a sequence of the transmission beams inresponse to the identification.
 15. The apparatus of claim 14, whereinthe instructions, when executed by the processor, further cause theapparatus to: perform a plurality of channel measurements of one of thereference signals during a symbol, wherein each of the channelmeasurements is associated with a different one of the reception beams.16. The apparatus of claim 15, wherein the instructions, when executedby the processor, further cause the apparatus to: identify adistinguishable beam pair for the one of the reference signals inresponse to the channel measurements; and refrain from performingsubsequent channel measurements with the distinguishable beam pair. 17.The apparatus of claim 14, wherein the instructions, when executed bythe processor, further cause the apparatus to: provide an indication ofa plurality of distinguishable beam pairs to the wireless device.
 18. Amethod of wireless communication at a first wireless device, comprising:providing a message to a second wireless device indicating a beamsequence conveyance mode; determining a sequence of differenttransmission beams; and associating a reference signal with each one ofthe transmission beams for transmission to the second wireless deviceaccording to the sequence.
 19. The method of claim 18, furthercomprising: receiving an indication of a plurality of distinguishablebeam pairs from the second wireless device in response to the message.20. The method of claim 19, wherein one of the distinguishable beampairs includes one of the transmission beams and one of a plurality ofreception beams, and wherein a difference between a first signalstrength of the reference signal associated with the one of thetransmission beams over the one of the reception beams and a secondsignal strength of the reference signal associated with the one of thetransmission beams over another of the reception beams exceeds a signalstrength threshold.
 21. The method of claim 20, further comprising:providing the signal strength threshold to the second wireless device.22. The method of claim 18, further comprising: receiving a capabilityreport from the second wireless device indicating a capability forperforming a plurality of channel measurements during a symbol lengthand for performing a number of reception beam switches over a definedtime period, wherein the message is provided in response to the report.23. The method of claim 22, wherein the report indicates a maximumnumber of reception beam switches that are performable by the secondwireless device during a time period over one of the transmission beams.24. The method of claim 18, further comprising: providing aconfiguration of transmission beam groups to the second wireless device,wherein different transmission beams constitute each of the transmissionbeam groups.
 25. The method of claim 24, wherein the transmission beamgroups are specific to the second wireless device.
 26. The method ofclaim 24, wherein two or more transmission beams of beam pairs having acommon reception beam are separated into different transmission beamgroups.
 27. An apparatus for wireless communication, comprising: aprocessor; memory coupled with the processor; and instructions stored inthe memory and operable, when executed by the processor, to cause theapparatus to: provide a message to a wireless device indicating a beamsequence conveyance mode; determine a sequence of different transmissionbeams; and associate a reference signal with each one of thetransmission beams for transmission to the wireless device according tothe sequence.
 28. The apparatus of claim 27, wherein the instructions,when executed by the processor, further cause the apparatus to: providea signal strength threshold to the wireless device.
 29. The apparatus ofclaim 27, wherein the instructions, when executed by the processor,further cause the apparatus to: receive a capability report from thewireless device indicating a capability for performing a plurality ofchannel measurements during a symbol length and for performing a numberof reception beam switches over a defined time period, wherein themessage is provided in response to the report.
 30. The apparatus ofclaim 27, wherein the instructions, when executed by the processor,further cause the apparatus to: provide a configuration of transmissionbeam groups to the wireless device, wherein different transmission beamsconstitute each of the transmission beam groups.